The Mekong River
There is no geographical feature that forms the border between Portugal and Spain. The Strait of Gibraltar and Mediterranean Sea separates Iberian Spain and Morocco. The Pyrenees Mountains forms the border between Spain and France and Spain and Andorra.
the yalu river
A border that follows a river or mountain range or similar natural feature.
The border across which genes can flow between two populations is called the contact zone. Natural selection operates to produce changes in populations.
This would be China and Russia to the southeast. The feature that separates these two countries is the Amur River.
The Yalu River is the border of China and North Korea.
The distance is about 2,520 air miles from border to border.
The Gobi desert
Vietnamese border raids in Thailand happened in 1979.
The border between Mexico and Texas is the Rio Grande River, also known as the Rio Bravo. The border between Arizona and the Mexican state of Baja California is the Colorado River (Rio Colorado), which also flows through the Grand Canyon and the Hoover Dam. The rest of the border between the United States of America and Mexico is made up of arbitrary straight lines, not corresponding to any natural feature.
The Great Lakes are part of the border between the USA and Canada.
The countris that border Thailand are Cambodia, Laos, Myanmar, and Malaysia
Actually, there are 4 countries which border Thailand. Burma, Laos, Cambodia and Malaysia.
Thailand's northern border is higher in latitude than the northern border of the Philippines.