The Shan race, known by the self-names of Tai, Pai, Lao, &c., occupies an area of country six times as large as the United Kingdom; yet, owing to the trading propensities of the race, the dialects spoken by the Shans differ so slightly that travellers from the Tonquin hills, Kwangsi, Yunnan, and Bhamo can converse with people at Zimmé and at Bangkok. In the earliest times we hear of the Shans under their tribal names stretching across China from east to west, and occupying the country between the Yangtsze and the Hoang Ho. From 1766 to 1122 B.C. they are supposed to have been the dominant power in China, since the Shang, or traders, the ruling dynasty during that period, were presumably of their race. Later on they spread over Southern China, forming a large ingredient in the kingdoms of Tsoo, Tsen or Tien, and Nan-Yueh, and extended into the valleys of the Irawadi, Salween, Meh Nam, and Meh Kong. The last of their tribes to leave Central China for Indo-China appear to have been the Chau Tai or Siamese, who were expelled from their seat in Kiangsi and Anhwei in the tenth century of our era. They were driven to the south-west into Kwangsi and Kweichau, where some of their tribes are still found, and a large body ultimately migrated into the Shan States to the south of Kiang Hsen. In the latter half of the thirteenth century the country occupied by the Shans was in a state of turmoil and unrest. The ancient principalities in Yunnan had been conquered by Kublai Khan 1253–54; the Shan States to the south and west of Yunnan had been attacked, and a consequent great displacement of the population occurred. At that time the agglomeration of States formed by the Ngai Lao or Lao Shans stretched southwards from the latitude of Kiang Hsen to the northern confines of Cambodia or La-Wek, which then included a number of principalities in the valley of the Meh Nam, as well as in that of the Meh Kong. About 1281, according to the Shan records at Zimmé, the Prince of Kiang Hsen advanced southwards and conquered Lapoon, and in 1294 founded the present city of Zimmé. The Lapoon Shans fled into Martaban, and, headed by one of themselves, attacked the Burmese governor, slew him, and made their leader Wa-re-ru King of Martaban, A.D. 1281. Six years later, this Shan king conquered Pegu, and Shan kings reigned over the joint kingdom from that time until they were conquered by the Burmese in 1540. Upper Burmah was likewise under Shan kings from A.D. 1290 to 1554.