Where in the world?
The flag of Chad has three vertical stripes of blue, yellow, and red.

Chad

Tchad

Population: 16,425,859

Region: Africa

Subregion: Middle Africa

Capital: N'Djamena

Top Level Domain: .td

Currencies: Central African CFA franc

Border countries

The flag of Cameroon has three vertical stripes of green, red, and yellow with a yellow star in the center.

Cameroon

Population: 26,545,864

Region: Africa

Capital: Yaoundé
The flag of the Central African Republic has four horizontal stripes of blue, white, green, and yellow with a red vertical stripe in the center and a yellow five-pointed star in the upper hoist-side corner.

Central African Republic

Population: 4,829,764

Region: Africa

Capital: Bangui
The flag of Libya has a horizontal triband of red, black, and green with a white crescent and star centered on the black stripe.

Libya

Population: 6,871,287

Region: Africa

Capital: Tripoli
The flag of Niger has three horizontal stripes of orange, white, and green with an orange circle in the center.

Niger

Population: 24,206,636

Region: Africa

Capital: Niamey
The flag of Nigeria has three vertical stripes of green, white, and green.

Nigeria

Population: 206,139,587

Region: Africa

Capital: Abuja
The flag of Sudan has three horizontal stripes of red, white, and black with a green triangle on the left side.

Sudan

Population: 43,849,269

Region: Africa

Capital: Khartoum