Ma-i or Maidh was an ancient sovereign state located in what is now the Philippines. Its existence was first documented in 971 in the Song dynasty documents known as the History of Song, and it was also mentioned in the 10th century records of the Bruneian Empire. Based on these and other mentions until the early 14th century, contemporary scholars believe Ma-i was located either in Bay, Laguna or on the island of Mindoro.

Research by Fay Cooper Cole for the Field Museum in Chicago in 1912 showed that the ancient name of Mindoro was Mait. Mindoro's indigenous groups are called Mangyans and to this day, the Mangyans call the lowlands of Bulalacao in Oriental Mindoro, Mait. For most of the 20th century, historians generally accepted the idea that Mindoro was the political center of the ancient Philippine polity.: 119 But a 2005 study by Filipino-Chinese historian Go Bon Juan suggested that the historical descriptions better match Bay, Laguna (pronounced Ba-i), which is written similarly to Ma-i in Chinese orthography.