WI: Romans in Crimea - Extension of Roman empire in Black Sea -

Romans in Crimea - Extension of Roman empire in Black Sea?

Why Romans did not settle Black sea region?
It provided fertile climate, sea access a calm waters.
What would impact be then?

If Romans could not take it easily which part of Roman empire was relative waste to this conquest?
 
During Imperial times, the Crimea belonged to the Bosporan Kingdom. The Bosporan Kingdom was a Helleno-Sarmatian client state of the Roman Empire. In this respect, it was similar to Kolchis / the post-Kolchean client states on the Eastern end of the Black Sea.

So the question is rather:
Why did the Romans not outright annex these client states?

Because Roman expansion did not necessarily follow the logic outlined in the OP:
It provided fertile climate, sea access a calm waters.
There were, indeed, sometimes conquests motivated by pure greed.
Much of the time, though, Roman conquests followed a vicious circle of previous expansion - disturbance of the outlying periphery - attacks on the new territories from the outlying periphery - further expansion - ...
In this logic, long-haired Gaul was conquered to protect the Roman province on the Mediterranean; and parts of Germania were conquered to protect Gaul.
The Crimea does not fit into any such logic.
For a conquest of greed, on the other hand, it was not attractive enough (lacking, for example, precious metals / ores) and at the same time rather dangerous (always threatened by steppe invaders).
Good land to settle your veterans on was still abundantly available within the Empire: all over the Balkans, for example. After Augustus` conquests, at the latest, the inner colonisation of the Empire remained an unfinished business, so why go dismember a functioning client state at the edge of the world just to have yet more fertile land at your disposal? Which you then have to defend with your own forces against Sarmatians, Alans, Goths, Huns, ...
 
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