Ma-i or Maidh (also spelled Ma'i, Mai, Ma-yi or Mayi; ) was a sovereign polity that pre-dated the Hispanic establishment of the Philippines and notable for having established trade relations with the Kingdom of Brunei, and with Song and Ming Dynasty China.
For many years, scholars believed that this state was likely to have been on the island of Mindoro. But recent scholarship casts doubt on this theory, arguing that historical descriptions better match Bay, Laguna (whose name is pronounced Ba-i), which once ruled over a vast territory on the eastern coasts of Laguna de Bay. Another suggested location is Malolos, Bulacan.
Its existence was recorded both in the Chinese Imperial annals Zhu Fan Zhi and History of Song and in the royal records Sultanate of Brunei, which refer to it as the nation of Maidh. The two possible sites that have been idenfitied by historians have similar names: according to sources, the precolonial name of Mindoro was "Ma-it"; historical variants of the name of Bay, Laguna include "Bae", "Bai", and "Vahi".
The Chinese and Bruneian records, which predate most of the local written sources extant in the Philippines today, are significant as they give historians a textual record of what life in precolonial Philippines was like.