Steve asked:
How long then before it develops a different, more advanced civilisation?
It seems to have developed a different, more deteriorated civilization.
Also, how is it guarded? Surely Blake wasn't the first person to think about breaking out some prisoners.
I bet the sticking point was transport--easy enough to take over, hard to go anywhere else. The Federation's POV may have been, OK, now you're in charge of a planet of convicted criminals. YOU try running the place. Knock yourself out.
-(Y)