From early times China was surrounded by states of lower culture, and on the whole, of lesser military power, which the Chinese regarded as protectorates or tributaries. As early as the Chou dynasty, interpreters were appointed to deal with envoys bringing tribute or declarations of loyalty. The Chou interpreters were called chi , hsiang , ti t'i , or i , and took charge of peoples from the east, south, west, and north respectively. The Ch'in dynasty bureaux of tributary affairs were the tien k'o and tien shu kuo , which the Han later replaced by the Ta Hung Lu under which there were interpreters (i kuan ). In the Sui, T'ang, and Sung dynasties tributary affairs were handled by the Ssŭ Fang Kuan (). In the Ming dynasty the Ssŭ I Kuan was founded to translate foreign diplomatic documents, and was continued in the Ch'ing with a change of name ( to ) and accompanied by the Hui T'ung Kuan, which handled oral interpreting.