Spain and the United States.
The Treaty of Tordesillas was signed in 1494 and divided newly discovered lands outside Europe between Spain and Portugal along a meridian line. The Treaty of Zaragoza in 1529 further defined the boundaries between the two countries in the East Indies and the Pacific Ocean.
A formal agreement between two countries is called a treaty or a pact.
The Pinckney's Treaty was the treaty that established friendly relations between the United States and Spain and defined the boundaries between the United States and the Spanish colonies. It was signed in October 1795.
Pinckney's Treaty was a treaty signed between the United States and Spain. It defined the boundaries between the United States and the Spanish colonies and guaranteed the United States navigation rights on the Mississippi River.
The Jay Treaty resolved various issues between the United States and Great Britain following the Revolutionary War. It addressed disputes over trade, boundaries, and British military presence in the Northwest Territory. It also helped to improve relations between the two countries.
An alliance or agreement between two countries :)
The Oregon Treaty
The Adams-Onis Treaty of 1819 settled the boundary dispute between the United States and Spain. It established the border between Spanish Florida and the United States, ceding Florida to the United States and defining the boundary along the Sabine, Red, and Arkansas rivers.
Because of the conflict between the countries
Portugal and Spain signed the Treaty of Tordesillas, which had to do with newly found lands, and how the two countries would divide that land between them. Both countries ratified the treaty in 1494.
a treaty is an agreement between two or more nations.