After the death of Alexander the Great in 323 BC., the rulers of the provinces divided the empire among themselves. Ptolemy, son of Lagos the Macedonian, asked to rule Egypt and his request was granted. He became the first ruler of the Ptolemaic dynasty, which ruled Egypt from 323-30 BC.
The Ptolemies continued to practice the ancient Egyptian tradition, which meant that they were the owners of the land and everything else in Egypt. Like the pharaohs, they were sacred; the Ptolemaic king was the state. In addition, the Ptolemies had an excellent system of administration and there was abundance in Egypt.
Ptolemy the First built the core of his military forces from the forces left by Alexander the Great. These experienced soldiers were able to form a strong army and navy. He was also interested in religious matters, and established a new unified form of worship to bring the Egyptians and Greeks nearer to each other, so that the religion would not be a reason for dissension. The city of Alexandria was also built during his rule, and became the capital of Egypt and the seat of the government.
During the rule of Ptolemy the Second and Ptolemy the Third, all activities, political, economic, cultural and social, flourished; Ptolemy the Second built the Library of Alexandria; it became a magnet for researchers, scholars of science, and men of letters. He also built an institute near the library, where scholars were received. Ptolemy the Second paid a great deal of attention to the economy and commerce and constructed the lighthouse of Alexandria to guide ships coming from all over the Mediterranean.
Egypt continued to flourish in the period of Ptolemy the Third, who built new temples and restored ancient ones. He achieved an architectural movement that had never happened before; he modernized the library and provided it with more books, making Alexandria the leading capital of the ancient world.
Then decadence in the dynasty set in with the ascension of Ptolemy the Fourth, who spent his time satisfying his lusts and pleasures. In addition the Egyptians revolted against him twice. The dynasty remained like this until the Romans conquered Egypt in 30 BC., and the country became a Roman province.