Ptolemy I, also known as Ptolemy Soter, was a general under Alexander the Great and became the ruler of Egypt after Alexander's death in 323 BCE. He founded the Ptolemaic Kingdom, which lasted nearly three centuries, and established the city of Alexandria, which became a major center of culture and learning. As a pharaoh, Ptolemy I promoted the blending of Greek and Egyptian cultures, known as Hellenistic culture. He also initiated the famous Library of Alexandria, which aimed to collect knowledge from across the known world, making it one of the most significant libraries of the ancient era.