Yilan County, alternately spelled I-lan, is a county in northeastern Taiwan. Yilan is the northernmost county on the island of Taiwan, with a population 450,031. Its seat is located in Yilan City.

Taiwanese indigenous peoples, also known as Formosans, Native Taiwanese or Austronesian Taiwanese, and formerly as Taiwanese aborigines, Takasago people or Gaoshan people, are the indigenous peoples of Taiwan, with the nationally recognized subgroups numbering about 569,000 or 2.38% of the island's population. This total is increased to more than 800,000 if the indigenous peoples of the plains in Taiwan are included, pending future official recognition. When including those of mixed ancestry, such a number is possibly more than a million. Academic research suggests that their ancestors have been living on Taiwan for approximately 15,000 years. A wide body of evidence suggests that the Taiwanese indigenous peoples had maintained regular trade networks with numerous regional cultures of Southeast Asia before the Han Chinese colonists began settling on the island from the 17th century, at the behest of the Dutch colonial administration and later by successive governments towards the 20th century.