Which preposition to use with szechwan

in Occurrences 2%

Meanwhile the governors of Szechwan in the west and Chekiang in the south-east made themselves independent.

to Occurrences 2%

The small states in Kansu, which dominated the route, now passed on the traffic along two routes, one northward to the Toba and the other alien states in north China, the other through north-west Szechwan to south China.

Which preposition to use with  szechwan