Answer: black sea empire
Explanation:Empire of the Black Sea: The Rise and Fall of the Mithridatic World. As you can see, the Romans practically had the Black Sea surrounded. If you study the map, the Mediterranean Sea was surrounded by countries with cities which meant trade goods, riches, etc., It was also the ‘open highway’ to every country that was civilized. Even though they did conquer most of the area around the Black Sea, you can see that that is a closed sea. If the land wasn’t rich in something they could use or needed, there wouldn’t be much need to keep much more than fortifications there to protect their empire from the marauders, The Roman Empire was huge for it’s time but it didn’t have the weapons like we have today so it stands to reason, they only had the manpower to protect so much empire. This is evidenced by the areas in pink, which at one time had been conquered by the Romans but was later given back to the original inhabitants simply because it was almost impossible to sustain at such a great distance….these areas remained “friendly” to the Roman Empire and didn’t attack them. Most of the outer edge of the green area was used as fortification against unknown peoples if Rome felt there was a possibility of a threat from that area. So basically it boils down to profit, protection and economics of providing for the region under its control.It would have been a third kind of territory for the Romans to take over — more difficult and less rewarding. The cost-benefit balance was against it, even if they could have done it, which is highly doubtful. Consider the areas the Romans did expand into. In the East, there were long established states, longer established than Rome, rich and powerful in their own right. The rewards are obvious. And while, had those states stood together, they could have resisted the Romans, they were in fact each others’ rivals and enemies, and some were always prepared to ally with Rome.
In the West, there were weak but settled polities, based around agriculture, whom Rome regarded as backwards, and who on balance might well have agreed. Again, Rome was able to take them out one by one, at least until it came up against the stronger and more entrenched polities of Germany, and having done so, to hold this settled territory fairly securely. These were not previously wealthy territories, so the balance of advantage was not as clear as in the East, but as long as the conquest and holding was not too costly, it could still be positive. In Germany, it proved too costly. The division was not quite as simple as East and West, and there were some examples of each kind of territory on each side, but those were exceptions, and the point is that these were all settled, agricultural territories that Roman methods could hold and defend. Now consider the lands to the north and east of the Black Sea. This was nomad country, occupied by herders not farmers. The polities formed by those herders were very aggressive, very unstable and very mobile. Conquer one and you would still have to deal with all the others across the entire breadth of Asia. Disturb the balance of power and new ones would rapidly form. And it was a land bereft of natural boundaries. If you could conquer it, how would you go about defending it? Roman methods were completely unsuitable. Romans were well aware of how dangerous the Scythians were. That was their name for the nomads. As far as they were concerned, it was wild, unrewarding territory with nothing in it to attract any civilised power. While they may not run a deliberate policy of keeping a buffer between themselves and the Scythians, they did regard the lands as getting increasingly wild and unrewarding the further you went in that direction, and by happy accident or design, it amounted to a buffer policy.
The Persians were half-nomad, and without such a buffer a new lot of nomads would periodically take their empire over. With slightly different geography, the same could have happened to Rome.
