'The City of Happiness') is a district (srok) in the south of Banteay Meanchey Province, in northwestern Cambodia.

The main railway line from Phnom Penh to Poipet on the border with Thailand runs through the district from north to south.

However, it has the largest district population in the province due to its central location and transport infrastructure.

National road 160 begins near the centre of the district and runs southwest into Pailin.

[2] The history of Mongkol Borey District before the 18th century is unclear, although it is likely that it was part of Battambang province.

Mongkol Borey is one of the largest agricultural districts in Banteay Meanchey Province.

Due to its geographical advantage, trading with the neighboring country, Thailand, also plays an important role in the district.

Due to the instability of farming, job seeking and aiming to improve the living condition have forced some of the population to flee hometown to the larger cities like Phnom Penh and Siem Reap for employment and schooling.