Simplify the following text for a Grade 11 native English-speaking person.
Original: The Montevideo Convention on the Rights and Duties of States was a treaty signed at Montevideo , Uruguay , on December 26 , 1933 , during the Seventh International Conference of American States .
Simplified: The treaty was signed at Montevideo , Uruguay , on December 26 , 1933 , at the Seventh International Conference of American States .