The first bridge over the Yellow River was constructed by the kingdom of Ts'in in 257 B.C., on what is still the high-road between T'ung-thou Fu and P'u-chou Fu. Previous to that date armies had to cross the Yellow River at the fords; and, as an instance of this, it may be stated that the founder of the Chou dynasty in 1122 B.C. summoned his vassals to meet him at the Ford of Mêng, a place still so marked on the maps, and lying on the high-road between the two modern cities of Ho-nan Fu and Hwai- k'ing Fu; thus there was no excuse for the feudal princes failing to arrive at the rendezvous. It was not far from the same place, but on the north bank of the river, that Tsin in 632 B.C. held the great durbar as Second Protector, on the notorious occasion when the puppet Emperor was "sent for" by the Tsin dictator. To conceal this outrage on "the rites," Confucius says: "The Son of Heaven went in camp north of the river." To go on hunt, or in camp, is still a vague historical expression for "go on fief inspection," and it was so used in 1858, when the Manchu Emperor Hien-fêng took refuge from the allied troops at Jêhol in Tartary. The first thing Ts'in did when it united the empire in 221 B.C. was to occupy all the fords and narrow passes, and to put them in working order for the passage of armies. As even now the lower Yellow River is only navigable for large craft for 20 miles from its mouth (now in Shan Tung), it is easy to imagine how many fords there must have been in its shallow waters, and also how it came to pass that boats were so little used to convey large bodies of troops with their stores.