https://www.reddit.com/r/AskHistorians/comments/d3hioi/how_did_people_learn_languages_in_the_middle_ages

In the meantime here is an example of this being answered before! (on mobile on the train, sorry I'm not formatting better).

Edit: u/coeurdelionne, u/welfontheshelf, and u/bristoneman all responded to this question (including links to even more previous asks)

In the Classical world (as might be expected), the circumstances, motivations, and methods of language learning varied considerably. The most famous group of language learners are of course the Roman elite, who were expected for centuries to have at least a reading knowledge of Greek. On a humbler social level, the tens of thousands of Roman merchants and colonists who settled in the Greek world had to learn enough of the language to go about their daily business. Many of the hundreds of thousands of slaves imported into Italy from the Greek world following the wars of the middle and late Republic, likewise, were expected to master at least rudimentary Latin. On a still grander scale, recruits in the Roman army had to absorb enough Latin to follow commands and communicate with their fellow soldiers.

We know most about about the Roman elite's methods of language learning. In his Institutes of Oratory, Quintilian suggests that Roman boys actually start their education with Greek, around the age of seven:

"I prefer that a boy should begin with Greek, because Latin, being in general use, will be picked up by him whether we will or no; while the fact that Latin learning is derived from Greek is a further reason for his being first instructed in the latter. I do not however desire that this principle should be so superstitiously observed that he should for long speak and learn only Greek, as is done in the majority of cases. Such a course gives rise to many faults of language and accent; the latter tends to acquire a foreign intonation, while the former through force of habit becomes impregnated with Greek idioms, which persist with extreme obstinacy even when we are speaking another tongue. The study of Latin ought therefore to follow at no great distance and in a short time proceed side by side with Greek. The result will be that, as soon as we begin to give equal attention to both languages, neither will prove a hindrance to the other." (1.1.12)

Training in Greek began with the alphabet, then proceeded to syllables, words, and finally sentences. More advanced language learning was a matter of rote memorization of literary passages and literal translation. A schoolbook from the fourth century contains parallel Greek and Latin descriptions of scenes from daily life, not unlike something you might see in a modern language textbook: a student gets up, goes to school, eats lunch, etc. The results of such training could be extremely impressive. A first-century inscription honors Quintus Sulpicius Maximus, a Roman boy already well-known for his poetic skill in Greek by the time he died at age 11. The epitaph is worth quoting:

In memory of Quintus Sulpicius Maximus, the son of Quintus, of the Claudian tribe. His home was at Rome. He lived eleven years, five months, and twelve days. In the third lustrum of the contest [Domitian's Capitoline Games], entering the competition as one among fifty-two Greek poets, he roused to admiration by his talent the favor he had won by his tender years, and came off with distinction. That his parents may not seem to have been unduly influenced by their affection for him, his extemporaneous verses have been inscribed below....."

Young Greeks seem to have learned Latin by a similar process, copying out lines of Virgil and laboriously proceeding from syllable to sentence. Plutarch comments, briefly and rather cryptically, on how he learned Latin:

" I live in a small city, and I prefer to dwell there that it may not become smaller still; and during the time when I was in Rome and various parts of Italy I had no leisure to practice myself in the Roman language, owing to my public duties and the number of my pupils in philosophy. It was therefore late and when I was well on in years that I began to study Roman literature. And here my experience was an astonishing thing, but true. For it was not so much that by means of words I came to a complete understanding of things, as that from things I somehow had an experience which enabled me to follow the meaning of words." (Life of Demosthenes 2)

Plutarch's comment that he proceeded from concepts to words may suggest that mature learners took a more global approach to language learning - but this may be reading too much into a mannered comment.

Proceeding to the second part of your question, about how peoples with no previous contact would communicate - in the classical world, at least, knowledge of Latin or Greek usually preceded conquering armies by centuries. Merchants and mercenaries were often linguistic pioneers, learning at least a smattering of the languages of their trading partners or employers. Sometimes, admittedly, such contact took place without translation. Herodotus reports how trade might happen without language:

"Another story too is told by the Carchedonians. There is a place, they say, where men dwell beyond the Pillars of Heracles; to this they come and unload their cargo; then having laid it orderly by the waterline they go aboard their ships and light a smoking fire. The people of the country see the smoke, and coming to the sea they lay down gold to pay for the cargo and withdraw away from the wares. Then the Carchedonians disembark and examine the gold; if it seems to them a fair price for their cargo, they take it and go their ways; but if not, they go aboard again and wait, and the people come back and add more gold till the shipmen are satisfied. Herein neither party (it is said) defrauds the other; the Carchedonians do not lay hands on the gold till it matches the value of their cargo, nor do the people touch the cargo till the shipmen have taken the gold." (4.196)

Typically, however, there were a few interpreters to facilitate trade with even distant countries. Pliny the Elder, for example, mentions how a Roman freedman happened to learn the language of Sri Lanka:

"Annius Plocamus had farmed from the treasury the revenues arising from the Red Sea. A certain freedman of his, while sailing around Arabia, was carried away by a gale from the north beyond the coast of Carmania. In the course of fifteen days he had drifted to Hippuros, a port of Taprobane, where he was most kindly and hospitably received by the king; and having, after a study of six months, become well acquainted with the language, was enabled to answer all his enquiries relative to the Romans and their emperor..." (6.84)

The freedman proceeded to facilitate a trade agreement between the king and the Romans.

There was, in short, always contact between far-flung peoples; and where there was cultural or monetary motivation for communication, a class of interpreters was sure to emerge.

It is first good to remember that learning a new language is a major endeavour, and a big investment of time and resources. Having a desire to learn other languages just for its own sake is a fairly modern ethos; if two ancient people came to contact and could not understand each other, they would not set out to learn the foreigner's speech unless there was a heavy social need to do so. [Also, a vague but interesting observation from my old notes on this topic: Momigliano in Ancient Wisdom and Isaac in The Invention of Racism have briefly speculated that many elite Greeks and Romans might have fostered an attitude that foreign languages could even have a corrupting effect, e.g. Cicero in de lege agraria 2.95 seems to imply that the Carthaginian language in itself leads to the desire to cheat and makes Carthaginians fraudsters and liars].

Arguably, in the Classical Greek Mediterranean the interest to learn foreign languages was extremely minimal - the Greeks were rather snobbish towards other ethno-linguistic groups (what could the barbaroi possibly have to say that was of interest!?) and in general most Greek communities were rather insulated from other linguistic cultures, apart from some localities: in Italy and Sicily (Magna Graecia), where e.g. Phoenician, Etruscan and Italic communities also flourished, or Asia Minor (modern Turkey), where local Anatolian languages like Luwian, Lycian and Carian were spoken to some extent. The one sphere of life where the Greeks would have come to contact regularly with other languages would have been cross-Mediterraenan trade, but minor trading operations can actually be done with minimal foreign vocabulary, e.g. numerical negotiations would have happened easily with just gestures and physical aids, like finger-numbers or counting stones. There were, of course, individuals who could be fluent or near-fluent in more than one language, but one imagines that the great majority of these people were people who got immersed in other languages "organically" - such as by growing up in a multilingual family or being a slave in one - rather than by consciously setting out to learn a new language. The more complex cross-cultural diplomatic negotiations or gathering information of foreign cultures for scholarly purposes, like what we find in abundance in Herodotus, would most often happen through interpreters who had learnt like this, immersing themselves in different language communities.

Things changed during Alexander and the Hellenistic era, when Greek kings came to rule huge non-Greek populations. The greatest imperative to learn a new language would have been among the native elites, who did not want to become completely marginalised from the now wholly Greek power structures. And, many enough locals managed to become fluent bilinguals, since we know of officials of various ranks with native names in the administration and armies of Hellenistic kingdoms. Our best evidence for language schooling from this period is from Hellenistic Egypt because of the rich papurys and ostraca finds, although my brief review has to be rather Hellenocentric (of course, already before and outside of the Greek influence the Egyptian society was multilingual, would be quite interested to hear what sort of schooling between different African languages there might have been if somebody knows!). Rafaella Cribiore has a great 2001 book on this, Gymnastics of the Mind: Greek Education in Hellenistic and Roman Egypt.

Education was mainly a private affair, and the great majority of language-learning would have happened within households. It was easiest to learn when you were young: one imagines that sometimes forward-thinking parents could place their children as wards or apprentices in Greek-speaking families. I don't know how much if any evidence we have of Egyptian children acquiring Greek education (generally speaking Egyptian and Greek communities lived "parallel" to each other in Ptolemaic Egypt rather than mixed), but at least in theory, if your family was lucky enough to be of some wealth and wanted their children to become literate, one could hire (or buy) a private Greek tutor, or send a child straight to the schools that Greek children used, which could be as simple as an entrepreneurial teacher charging a fee from a group of local children who met up regularly somewhere in open-air. There, the child - assuming he or she was resilient enough to overcome the initial language barrier and able to follow instruction - could learn Greek as they were learning to write and speak it. Teachers of these schools tended to teach both basic literacy and arithmetic. The model of instruction, based on the surviving ostraca and papyrus finds, was fairly simple: the teacher wrote down model alphabets and later increasingly complex set phrases, which the students would copy. The set phrases were often maxims, hexameter poems ("Begin, good hand, beautiful letters, and a straight hand!" as an example from a Roman era document p. 133 in Cribiore) or lines from classics like Homer. Of course, only children that had ambitions to get a literate profession like scribe or in adminstration would attend this sort of schooling - the great majority of people were illiterate in Egypt and would rely on scribes if they needed any official paperwork done.

Were there any places in Hellenistic Egypt dedicated specifically for non-Greek speakers to learn Greek? Evidence is later from Roman era, but it seems some institutions that taught Demotic scribes could offer also Greek training. The use and teaching of the Demotic script had traditionally been fairly exclusively an affair of Egyptian religion (though of course used also in administration), and some teaching material finds suggest that long into the Roman era there were still writing schools associated with priests. A couple of these have yielded some limited number of Greek writing exercises, too. Learning to write in two languages simultanously must have been a heavy load: one Demotic ostracon quoted by Cribiore (p. 23) amusingly preserves a complaint of a student: "I will not write Greek letters: I am stubborn." Lot of the evidence from these "schools" is still unpublished so it is difficult to say just how extensively and what sort of Greek teaching they offered. The study and analysis of linguistic grammar was more or less invented in Hellenistic Alexandria, but I am not sure how early on grammars, which were directed for language-learners and which are known from later Roman era, started to be circulated. These grammars had grammatical paradigms and explanations of syntax in them. However, the convention was that the grammars were written in the language under discussion, so Greek grammars were written in Greek, and therefore required a very good level of Greek to understand them and not sure how available and helpful they would have been for Hellenistic or later Egyptian students.

While ambitious Egyptians had many reasons to learn Greek, it seems that this again very rarely went to the opposite direction. While the Greek Ptolemaic administration was bilingual and did produce e.g. carved hieroglyph monuments and Demotic documents (cf. Rosetta stone), with great likelihood the people behind them were Egyptian officials who had acquired Greek, not the other way around. Reportedly Cleopatra (the famous one) did learn Egyptian to speaking proficiency among other languages, but she would have been the first of Ptolemaic ruler to do so after over 200 years of Greek monarchs. She most likely learnt by conversing with private tutors - and it seems unlikely that she would have spent the time to learn the complex Demotic script herself.

e. while I was writing this looks like u/toldinstone gave a nice answer with more experts from source material, hope mine somewhat compliments it!

Hopefully my question is relevant enough to stay on this thread: how would the Romans figure out the languages of Gallic tribes, be they uncontacted or not? Considering the fact that they were at war with the Romans more often than the Greeks, and I suppose it can be said that they were less liked, too.