Where in the world?
The flag of Senegal has a green, yellow, and red vertical tricolor with a green star in the center.

Senegal

Sénégal

Population: 16,743,930

Region: Africa

Subregion: Western Africa

Capital: Dakar

Top Level Domain: .sn

Currencies: West African CFA franc

Border countries

The flag of Gambia has three horizontal stripes of red, blue, and green, separated by thin white stripes.

Gambia

Population: 2,416,664

Region: Africa

Capital: Banjul
The flag of Guinea has three vertical stripes of red, yellow, and green.

Guinea

Population: 13,132,792

Region: Africa

Capital: Conakry
The flag of Guinea-Bissau has two horizontal stripes of yellow and green, with a red vertical stripe on the hoist side containing a black star.

Guinea-Bissau

Population: 1,967,998

Region: Africa

Capital: Bissau
The flag of Mali has three vertical stripes of green, yellow, and red.

Mali

Population: 20,250,834

Region: Africa

Capital: Bamako
The flag of Mauritania has a green field with a gold star and crescent in the center, and two red stripes at the top and bottom.

Mauritania

Population: 4,649,660

Region: Africa

Capital: Nouakchott