[2] The district is named after King Mengrai, the founder of the Lanna kingdom of northern Thailand.

Tambon Phay Mengrai is the site of a 2,700 rai Cavindish banana plantation owned and operated by the Chinese firm, Hongta International, a major local employer.

The Cavendish banana is controversial as its cultivation requires the intensive use of chemical pesticides to yield harvests for export.

[3] The Mekong-Lanna nature conservation network has accused the Chinese plantation of heavy use of pesticides and excessive water takings from Mae Ing Creek.

[4] The district is divided into five sub-districts (tambons), which are further subdivided into 69 villages (mubans).