Complex sentence: Lower Egypt ("al-Diltā") is the northernmost region of Egypt: the fertile Nile Delta, between Upper Egypt and the Mediterranean Sea--from El-Aiyat, south of modern-day Cairo, and Zawyet Dahshur.
Split into simpler sentences: Lower Egypt ("al-Diltā") is the northern-most section of Egypt. It refers to the fertile Nile Delta region, which stretches from the area between Upper Egypt and the Mediterranean Sea--from El-Aiyat south of modern-day Cairo, and Zawyet Dahshur.