Moving west from Paotowchen there is only one highway, which many camel trains from Kansu follow in winter, but which is almost deserted in summer when the Yellow River is ice free. This road leads through Santaoho, a Roman Catholic Mission village near the elbow of the river, through Shihtsuishan, where there is a carefully guarded pass and a large garrison, and on into the populous Ninghsia district of Kansu, altogether an eighteen day journey of about 1,300 11 through thinly settled country in which a pestilence would travel with difficulty and in which it could have been most effectually checked at any of half a dozen points.]