Simplify the following text for a Grade 10 native English-speaking person.
Original: The Territory of Oklahoma was an organized incorporated territory of the United States that existed from May 2 , 1890 , until November 16 , 1907 , when it was joined with the Indian territory and admitted to the Union as the State of Oklahoma .
Simplified: Oklahoma Territory was an organized territory of the United States from May 2 , 1890 until November 16 , 1907 , when Oklahoma became the 46th state .