The Hmong people are a minority ethnic group in several countries, believe by some researchers to be from the Yellow Basin area in China. The Hmong are known in China as the Miao, a designation that embraces several different ethnic groups. There is debate about usage of this term, especially amongst Hmong living in the West, as it is believed by some to be derogatory, although Hmong living in China still call themselves by this name. Chinese scholars have recorded contact with the Miao as early as the 3rd Century BCE, and wrote of them that they were a proud and independent people. However, after the Han Chinese attempted to impose several new taxation systems and continued expansion of their empire, the Hmong are reported to have rebelled. Many wars were fought, and eventually many Hmong were pushed from China into Burma (Myanmar), Laos, Thailand and Vietnam. The history of the Hmong people is difficult to trace; they have an oral tradition, but there are no written records except where other people have encountered them. Hmong history has been passed down through legends and ritual ceremonies from one generation to another.