Sheikh Khalifa served as the President of the UAE and ruler of Abu Dhabi since November 3, 2004. The Ministry of Presidential Affairs has announced 40 days of mourning for the passing of His Highness Sheikh Khalifa bin Zayed Al Nahyan, UAE President and ruler of Abu Dhabi, the Khaleej Times reported.

from Times of India https://timesofindia.indiatimes.com/world/middle-east/uae-announces-longtime-ruler-sheikh-khalifa-bin-zayed-al-nahyan-has-died-country-to-begin-40-days-of-mourning/articleshow/91541139.cms