The Diadem snake is distributed across Northern Africa  Morocco and Western Sahara, Libya, Egypt, Algeria, Niger, Mauritania, Mali, Northern Sudan and Syria, through the Middle East (Jordan, Turkey, Iran, Iraq, Kuwait, Oman, Arabia, United Arab Emirates, Saudi Arabia, Yemen, Afghanistan, Turkmenistan, Kyrgistan, Tajikistan, Uzbekistan) through to Pakistan and India (S. d. schirazianus only).

Subspecies S. d. cliffordii specifically occurs in a band across North Africa and the Middle East from Morocco all the way across North Africa through to Iraq, Iran, Yemen and UAE. This subspecies seems to be separated from S. d. schirazianus by the Zagros mountains in Iran. The type locality for S. d. cliffordii is Tripoli, Libya.

Virtually all of the specimens that will be present in the hobby will have originated from Egypt, which frequently exports reptiles in great quantities - although the Egyptian exporters may well collect outside the country’s borders as well (which would seem to be the case due to the presence of several non-Egyptian species frequently advertised on their lists).