Iu Mien Americans (Meiv guoqc Mienh) are primarily former refugees of the Secret War in Laos and the Vietnam War. While some Iu Mien families were granted political asylum and the opportunity to resettle in the United States prior to 1980, the great majority of Iu Mien immigrants to the U.S. arrived following the Refugee Act of 1980. Between the late 1970s to the early 1990s, thousands of Mien immigrants resettled mainly on the West Coast of the U.S. Today, the Iu Mien American population is estimated to be at 50,000 - 70,000.

With regard to ethnicity, the Iu Mien are officially classified in China and most of Southeast Asia as a subgroup of the Yao ethnicity. In Vietnam, however, the term Yao is referred to as Dao. Further classification of the Yao ethnicity brings up three major groups: Pan Yao, Bunu Yao, and Pingdi Yao. The Pan Yao group is the largest in China and Southeast Asia, and it is this Pan Yao group that Iu Mien Americans belong.

The Yao ethnicity was officially recognized by the Chinese government in the 1950s. The newly established Chinese communist government embarked on a project of "ethnic classification" that aimed to formally acknowledge the diverse ethnic groups within China. To accomplish this, government research teams were formed and tasked with studying common geographic regions, languages, cultural traditions, physical characteristics, and other defining factors. Upon completion of the project, the Yao or Yaozu people were officially recognized as one of the fifty-four ethnicities in China (list of ethnic groups in China). In 1974, an additional ethnicity (Jino) was included, bringing the total number of recognized ethnicities to fifty-five.

However, the Iu Mien, along with other subgroups classified as Yao, do not refer to themselves as "Yao." For the Iu Mien, they often refer to themselves as Iu Mien or Mien.

Although ancient Chinese records about the Yao (Mien) are inconsistent, they tend to converge around the idea that tribes residing in the northern Hunan province, near Dongting Lake and its "Five Streams," shared a common ancestry and cultural heritage. Southern China, before the Qin dynasty (221 BCE), encompassed territories beyond the Han Chinese heartland, which were inhabited by diverse tribal groups, some indigenous to the region and others not. Chinese states often categorized these tribal groups into designated geographical networks for administrative convenience.

The terms "Man" (barbarians), "Nanman" (southern barbarians), "Jing Man" (Chu barbarians), and "Yiren" (uplanders) are general classifications that encompassed various groups. Even variations of Yao, such as Moyao, Yaoren, and Manyao, were not limited to a particular ethnicity or tribal group. Nonetheless, it is widely acknowledged that some of the indigenous groups inhabiting the Dongting Lake region in ancient China are the forebears of the Yao people today.

According to certain Yao (Mien) texts and narratives, the Mien people were once inhabitants of a place known as "Qianjiadong," translated as "Thousand Family Grottos." The story goes that this stunning and tranquil valley could only be accessed via an unremarkable cave, which was also the only way in or out. The fabled homeland was reputedly encircled by cascading waterfalls and rivers, far removed from the outside world. Although some people question whether Qianjiadong ever existed, scholars in China have discovered evidence in Hunan province that may indicate its plausible location.

Around the 10th century, and possibly earlier, the Yao (Mien) tribes in the Hunan region initiated a migration towards Southern China. Some groups ventured into more southerly provinces such as Guangdong and Guangxi, while others headed southwest into Guizhou and Yunnan. Over the ensuing centuries, various Mien subgroups in China migrated into Southeast Asia, initially settling in Vietnam and later expanding into Laos and Thailand. As highland farmers coexisting with other hill tribes in northern Laos, the Mien became part of the French Indochinese administrative system. However, the French departed from Laos and Southeast Asia entirely in the 1950s, creating a vacuum that was filled by the United States.