Complex sentence: During the 8th to 7th centuries BC, Napata was the capital of the Nubian kingdom of Kush, whence the 25th or Nubian Dynasty conquered Egypt, whose rule is also known as the "Napatan period" of Egypt.
Split into simpler sentences: During the 8th to 7th centuries BC, Napata was the capital of the Nubian kingdom of Kush, whence the 25th, or Nubian Dynasty conquered Egypt. The rule of the 25th dynasty is also known as the "Napatan period" of Egypt.