The natural border between the northeast and midwest appalachian mountains mississippi river mason-dixon line

This is where the south and the north are divided, it is the border betweeen Pennsilvainya and Maryland

the correct answer is the following is a list of inventions made in the medieval islamic world, especially during the "islamic golden age" (8th to 13th centuries),[1][2] as well as the late medieval period, especially in the emirate of granada and the ottoman empire.

science and technology in the islamic world adopted and preserved knowledge and technologies from contemporary and earlier civilizations, including persia, india, china, and greece-roman antiquity, while making a number of improvements and innovations.