The Egyptians were a practical people and this is reflected in their astronomy in contrast to Babylonia where the first astronomical texts were written in astrological terms. Even before Upper and Lower Egypt were unified in 3000 BCE, observations of the night sky had influenced the development of a religion in which many of its principal deities were heavenly bodies. In Lower Egypt, priests built circular mudbrick walls with which to make a false horizon where they could mark the position of the sun as it rose at dawn, and then with a plumb-bob note the northern or southern turning points (solstices). This allowed them to discover that the sun disc, personified as Ra, took 365 days to travel from his birthplace at the winter solstice and back to it. Meanwhile, in Upper Egypt, a lunar calendar was being developed based on the behavior of the moon and the reappearance of Sirius in its heliacal rising after its annual absence of about 70 days.