The Pythagoreans were a group of ancient Greek philosophers and mathematicians who followed the teachings of Pythagoras, a prominent figure in the 6th century BCE. They are best known for their contributions to mathematics, particularly the Pythagorean theorem, which relates the lengths of the sides of a right triangle. The Pythagoreans believed that numbers were the essence of all things and studied their properties extensively. In addition to mathematics, the Pythagoreans also explored concepts in philosophy, music, and astronomy. They believed in the idea of harmony and that mathematical relationships could explain the natural world. Their influence extended beyond mathematics, impacting later philosophical thought and the development of science.