Where in the world?
The flag of Djibouti has two equal horizontal bands of light blue and green with a white isosceles triangle based on the hoist side containing a red five-pointed star.

Djibouti

Population: 988,002

Region: Africa

Subregion: Eastern Africa

Capital: Djibouti

Top Level Domain: .dj

Currencies: Djiboutian franc

Border countries

The flag of Eritrea has three horizontal stripes of green, blue, and red with a gold olive branch in the center.

Eritrea

Population: 5,352,000

Region: Africa

Capital: Asmara
The flag of Ethiopia has three horizontal stripes of green, yellow, and red with a blue circle and a yellow star in the center.

Ethiopia

Population: 114,963,583

Region: Africa

Capital: Addis Ababa
The flag of Somalia has a light blue field with a white five-pointed star in the center.

Somalia

Population: 15,893,219

Region: Africa

Capital: Mogadishu