Egyptians are an ethnic group of people originating from the country of Egypt. Egyptian identity is closely tied to geography. The population is concentrated in the lower Nile Valley, a small strip of cultivable land stretching from the First Cataract to the Mediterranean and enclosed by desert both to the east and to the west. This unique geography has been the basis of the development of Egyptian society since antiquity. The daily language of the Egyptians is a continuum of the local varieties of Arabic; the most famous dialect is known as Egyptian Arabic or Masri, which is a mix between Coptic and Arabic. Additionally, a sizable minority of Egyptians living in Upper Egypt speak Sa'idi Arabic, a mix between the Sahidic Coptic dialect and Arabic. Egyptians are predominantly adherents of Sunni Islam with a Shia minority and a significant proportion who follow native Sufi orders.