I reckon the value lies in its flatness and fertility contrasted with the mountainous land opposite. The land must have been so much more productive than the leached out and vertical uplands. Drier too as it still is. Any thoughts on its English name? Island of the Angles or island in an angle? (the latter is the meaning of Anglesey in the Cambridgeshire fens)

Coming back to the original question - pass. Central as a trading centre?