Where in the world?
The flag of Mongolia has three vertical stripes of red, blue, and red, with the national emblem centered in the blue stripe.

Mongolia

Монгол улс

Population: 3,278,292

Region: Asia

Subregion: Eastern Asia

Capital: Ulan Bator

Top Level Domain: .mn

Currencies: Mongolian tögrög

Border countries

The flag of China has a red field with five yellow stars in the top left corner, one large star surrounded by four smaller stars in a semicircle.

China

Population: 1,402,112,000

Region: Asia

Capital: Beijing
The flag of Russia has three horizontal stripes of white, blue, and red.

Russian Federation

Population: 144,104,080

Region: Europe

Capital: Moscow