More than I could fit in a post on reddit!

It is true that our source base for the Ancient Greek world is enormously unbalanced; Athens is really the only state we can claim to be well-informed about, with Sparta in very distant second place. This is partly due to the prominence of Athens as a centre of political, military and cultural activity during the Classical period, and partly to Athens' role as the "school of Hellas", which meant that a much greater share of Athenian literary production is preserved for study than of any other Greek community. There are many things we claim to know about "the Greeks" that we really only know for sure about Athens (and sometimes Sparta). There are many other things that we know very well from Athens, and see elsewhere only in little fragments or isolated mentions. To name just one example, we know about the rights of women in only three Greek states: Athens (because of numerous rhetorical and philosophical texts), Sparta (because of Athenians' fascination with Spartan laws) and Gortyn on Crete (because of the chance survival of a legal inscription).

That said, we're not completely in the dark about states other than Athens and Sparta. Firstly, non-Athenian authors do survive. Herodotos was from Halikarnassos in Karia; Pindar was from Thebes; Diodoros from Agyrion in Sicily; Plutarch, the prolific moral philsopher and biographer, was from Chaironeia in Boiotia. There are many others. Secondly, even Athenian authors would frequently write in detail about other communities; Xenophon's Hellenika, for instance, contains lengthy episodes in the history of Phleious, Elis and Sikyon. Plato and Aristotle (the latter not technically an Athenian) used the constitutions of other states as a foil in their quest for the ideal political system. Thucydides gives us important glimpses into the early history of Greek communities in Sicily and Western Greece. Histories, philosophies, biographies, and Pausanias' travel guide of Greece provide sometimes questionable, sometimes invaluable snippets of the history of less prominent states that we can often string together into something resembling a narrative. Thirdly, there is archaeology; most Greek states have left behind still-visible ruins and still-traceable material culture. From these sites we also get thousands of inscriptions that can tell us the names, deeds, values and customs of the people who lived there.

The trouble with all this information is that it comes to us as a heap of fragments. If we want to know the history of Athens and Sparta in the Peloponnesian War, we pick up Thucydides; but if we want to know the history of Orchomenos or Klazomenai, we have no such text to turn to. It takes familiarity with a broad range of sources to know where the information is (and it can turn up in unexpected places), and it takes a lot of training to piece together a story from what little we have. It is not impossible - but it is practically impossible for the casual reader. We rely on experts to do the hard work and compile the material for us. And then we lean heavily on works like Tomlinson's Argos and the Argolid from the End of the Bronze Age to the Roman Occupation (1972) or Buck's A History of Boeotia (1979) or other regional histories. Those who are not "in the know" about recent interpretations and excavations are unlikely to have anything to add to such works. But there is enough to be said to fill these books, and no way to sum them up in just a few paragraphs.

Just to give you a sense of this: Boiotia is one of the major plains of central Greece, famous in Antiquity for high-quality wheat (the best in the world, according to Roman authors) and for the eels that were fished from the now-drained Lake Kopais (which were a delicacy in Athens, and sorely missed during the Peloponnesian War, according to the comedian Aristophanes). While the region borders the Euripos Strait in the east and the Gulf of Corinth in the south, it has no good natural harbours, and was stereotyped by the Athenians as a rural backwater. However, it was the setting of a significant share of Greek mythology (Thebes was the city that Oidipous returned to, for example), produced some enormous names in Archaic and Early Classical poetry (like Hesiod and Pindar), and contained many wealthy smaller states besides Thebes, the main regional power. The nature of Boiotia as a plain at the crossroads between Northern and Central Greece made it a frequent battleground, and many of its towns are primarily known today as the sites of major pitched battles (Plataia, Tanagra, Delion, Koroneia, Leuktra, Chaironeia). This earned Boiotia the nickname "the dancefloor of Ares" (Plutarch, Moralia 193e). It features prominently in all historical accounts; Plutarch, being a native of the area, wrote the biographies of the major Theban historical figures Pelopidas and Epameinondas (though the latter work is lost). You can imagine that there is more to say about Boiotia than I could casually type out.

Indeed, even about Thespiai, which is just one of the many smaller city-states within Boiotia, we know more than I can easily sum up here. Apart from its long and troubled history with Thebes as the latter state sought to dominate all Boiotia, Thespiai's greatest claim to fame is that its men stayed behind with Leonidas on the third day of the battle of Thermopylai, and fought to the death alongside the 300 Spartans. In terms of military history, it was a place marked by great courage and terrible luck; at Delion in 424 BC, its contingent stood and fought to the death against the Athenians, which cost the town nearly all of its men of fighting age. The funerary inscription commemorating the disaster spans 9 slabs of stone; its legible part lists 101 names. With no defenders left, Thespiai was powerless to stop the Thebans demolishing their city wall to keep them subjected to Thebes (Thucydides 4.133.1). At the battle of the Nemea a generation later (394 BC), the Thespians were the only Boiotian contingent to encounter a stubborn enemy (the men of Pellene), resulting in another bloodbath (Xen. Hell. 4.2.20). After all this, the Thespians deeply resented Theban overlordship, and resisted it whenever they could. At the battle of Leuktra (371 BC), the Thebans so mistrusted their Thespian allies that they allowed them to desert en masse before the battle rather than risk them changing sides in the middle of the fight. When Alexander the Great came to punish the Thebans for rebelling against him in 335 BC, the Thespians declared that they were on his side.

I'm not sure if there is anything specific you'd like to know about these places, or about other states in the Greek world. As I hope I've made clear, our knowledge is often patchy, but often there's still quite a lot to say.