Island Bayou is a 46 miles (74 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Red River in Oklahoma

Oklahoma

Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

.

The stream rises northwest of Calera

Calera, Oklahoma

As of the census of 2000, there were 1,739 people, 676 households, and 469 families residing in the town. The population density was 678.6 per square mile . There were 742 housing units at an average density of 289.5 per square mile...

 in Bryan County

Bryan County, Oklahoma

Bryan County is a county located in the U.S. state of Oklahoma. The population was 36,534 at the 2000 census. Its county seat is Durant. The county shares the same boundaries as the Durant Micropolitan Area. It is also home to the headquarters of the Choctaw Nation of Oklahoma located in Durant...

 and flows southeastward before emptying into the Red River south of Wade. Its entire length is within Bryan County.

The Treaty of Doaksville (1837) set Island Bayou as the boundary between the Chickasaw

Chickasaw Nation

The Chickasaw Nation is a federally recognized Native American nation, located in Oklahoma. They are one of the members of the Five Civilized Tribes. The Five Civilized Tribes were differentiated from other Indian reservations in that they had semi-autonomous constitutional governments and...

 and Choctaw Nations

Choctaw Nation of Oklahoma

The Choctaw Nation of Oklahoma is a semi-autonomous Native American homeland comprising twelve tribal districts. The Choctaw Nation maintains a special relationship with both the United States and Oklahoma governments...

 in Indian Territory

Indian Territory

The Indian Territory, also known as the Indian Territories and the Indian Country, was land set aside within the United States for the settlement of American Indians...

; however, the description was uncertain.