There absolutely were!

The reason Rome is so remarkable is that it was the juggernaut of its age; almost every gain you saw on that map is the result of a major, brutal war against one of its neighbors. That being said, the characteristics of those people were often very different from Rome herself.

The most directly comparable nations to Rome in her own time were generally centered around the Mediterranean. The reasons for this are controversial, but one of the most common explanations is the fact that the Med provides an easy seaborne trade route. We forget in our modern age of planes, trains, and automobiles how arduous overland transport used to be; when your only option to ship bulk goods on land was a long, slow, and often painful wagon ride, you might be forgiven for preferring to put your wheat or marble or wine amphorae (jars) on a faster and larger ship to cover the same distance for a fraction of the time and effort.

For this reason (and probably also because of the immensely fertile soil and high levels of sunshine and rain throughout the year), large, agriculturally-based societies sprung up in places like modern Italy, Greece, Egypt, and Tunisia. These Big Four (Rome, Greece, Egypt, and Carthage) had attained by the tail end of the Hellenistic period (for our purposes, say 160 BCE) a high degree of urbanization - that is to say, their cities had developed into hubs of trade and commerce above and beyond the traditional village role as a smallish hub of a subsistence farming community. Cities like Alexandria and Rome had attained populations in the ballpark of one million people by some estimates, a remarkable achievement for their times. This population growth was partially a result of the conquest of each empire's immediate neighbors: if you don't have to worry about raids from the Samnites next door every year, your city needn't stay strictly inside a tight defensive perimeter, and a larger portion of your army can be devoted to campaigns further away from home.

Without getting into a full political science lecture of each empire of Classical Antiquity, it will suffice to say that each of these empires were tightly centralized by the standards of their time: the city of Rome directly ruled all the land south of the river Rubicon, and beyond that frontier to the north and across the Adriatic and Mediterranean their holdings were ruled by proconsuls, roughly equivalent to a military governor. Much the same could be said of Carthage and its holdings in North Africa and Spain, though the latter would become something of a "rebellious province" on account of the personal ambitions of the Barca military family (Hamilcar, and his famous sons Hannibal and Hasdrubal). Egypt and Greece, on the other hand, were political remnants of Alexander the Great's empire, and though their structures were monarchical rather than council-based, they still wielded a commanding influence over their subjects.

On the other hand, many civilizations to the north of the Mediterranean had not yet reached this level of political and economic sophistication yet. Tribes like the Cimbri and the Teutones lived in largely migratory communities; they would move around the lands currently known as Germany, France, and Switzerland in search of better grazing lands for their livestock and better soil for their crops once each had been depleted in their old location. Occasionally these groups would get very large indeed, numbering some hundreds of thousands of men, women, and children with some tens of thousands of fighting men each. It's tempting to view them as barbarians plain and simple, but I've seen some convincing cases made that these groups closely resembled Greece as it was on the threshold of democracy. As Rome expanded her frontiers beyond Italy itself, the borders of the empire (with a small "e", as Rome was still a Republic at this time) rubbed up against the lands of several of these tribes, and a market formed as markets are wont to do. We have significant archaeological evidence of Roman wine amphorae and jewelry from Greece being traded in communities as far north as modern Belgium when the frontiers of Rome herself were still hundreds of miles away; likewise, we have evidence of coal from Britain first coming to be used in Roman jewelry around the same time period. But as with any instance of close contact between a wealthy civilization and a poor civilization, the poor will soon come to covet that for which they have developed a taste but cannot make themselves.

Some time around 110 BCE, the Cimbri tribe had completed a migration down from its homeland in modern Denmark and northern Germany and arrived in modern central France, within a few months' march of Rome. By all accounts the Cimbri were a very large tribe, perhaps numbering over three hundred thousand when combined with a neighboring group, the Teutones. It was shortly after their arrival in this region that the nearby Roman proconsul and the Senate back in Rome started to become understandably nervous about the prospect of - as they saw it - a horde of screaming barbarians, 300,000 strong, descending on their territory. This is, in fact, exactly what happened: the Cimbri and the Teutones dealt Rome several crushing defeats in encounter after encounter, killing tens of thousands of Roman legionaries in the process. So badly depleted was Rome's fighting strength that a man named Gaius Marius was chosen to handle the problem and reform the military to fight another day. These reforms would have huge consequences on Rome's politics within a few decades, but in the short term they allowed Marius to defeat first the Cimbri and the Teutones who had made the fatal blunder of sparing Italy when it was wide open in favor of plundering Spain instead.

Some years later, the Roman proconsul of the province of Cisalpine and Transalpine Gaul became worried of a repeat of the Cimbrian and Teutonic Wars when a tribe called the Helvetii began to migrate from modern Switzerland to France by way of Roman territory. It wasn't an irrational fear: this governor may not have remembered the war against the Cimbri himself, but he was the nephew of Gaius Marius by marriage and understood intimately the threat such an event could pose. The Helvetii were not such a small tribe themselves, probably over one hundred thousand people, and to defeat them the proconsul enlisted the help of other Gallic tribes allies to Rome. Over time, the need to protect these allied tribes and to pacify the lands Rome had de facto come to rule through the defeat of their kings and leaders.

The British Empire was once described as having "conquered the world in a fit of absence of mind". Julius Caesar's conquest of Gaul (modern France, Belgium, and parts of the Netherlands and Germany) might well fit that description; though it certainly helped his career greatly, there is little evidence to suggest that he intended from the get-go to conquer quite as much land as he eventually would.

What is not in doubt is that there were hundreds of thousands of people on that land. Caesar himself wrote yearly dispatches to the city of Rome (largely intended for a public audience rather than as military briefings) called Commentaries; this compendium of works has survived down to the present day, and the one thing it makes very clear is how many Gallic tribespeople died during the Roman conquest of their homeland. Some accounts place the number of "tribes" within Gaul as high as 60, each with tens of thousands if not hundreds of thousands of people under their control. What must be understood is that these were whole civilizations in and of themselves; it is not for nothing that Caesar's eight-year conquest of the whole of Gaul is widely recognized as one of the most incredible of all historical feats of generalship.

By Caesar's own figures, the number of those killed during his campaigns may well have reached as high as one million. Some modern historians think this number a little high, but it is not in doubt that the Gallic legions were directly responsible for the deaths of tens of thousands of fighting men and perhaps far more women and children to boot.

tl;dr: Yeah, and it really sucked to be one of them when Rome came knocking.

Sources: I leaned pretty heavily on the works of Adrian Goldsworthy here; his book "Caesar" is a great read if you ever feel inclined to learn more about Rome during his time period. I also have a pretty solid grasp of Caesar's Commentaries themselves - the prose is a little spartan, but it's a must-read for anyone into military history.