By Martin Plaut
BBC Africa analyst
The Sultan of Sokoto, Muhammadu Maccido, who has died in a plane crash near Abuja, was the spiritual leader of Muslims in Nigeria and Niger.
The Sultan of Sokoto heads Nigeria's 70m Muslims
A man revered across a large swathe of West Africa, he has held the position since April 1996.
The sultan was not a religious leader himself, but someone to whom Muslims looked to for leadership and guidance.
For example, it was he who announced the timing of Muslim occasions, like Ramadan.
And when there were important issues facing the region's Muslims, he was their spokesman.
The sultan will be remembered for his intervention to end the sporadic clashes that break out between Nigeria's Muslims and Christians.
SULTAN OF SOKOTO
Leads Nigeria's 70m Muslims
Sokoto base for 19th Century jihad, spreading Islam across northern Nigeria
Sokoto still Nigeria's centre for Islamic learning
His appointment was not without controversy.
Muhammadu Maccido was believed to have been the choice of the traditional kingmakers of Sokoto, but was prevented from taking the position by President Ibrahim Babangida in 1988.
It was only when former military ruler Sani Abacha removed Sultan Ibrahim Dasuki that he took finally took on the role.
Muhammadu Maccido will be widely mourned - and a spokesman for President Obasanjo has spoken of the country's deep shock and sadness.