Analysis of information sources in references of the Wikipedia article "Al-Musta'in (Cairo)" in English language version.
But not a single one of them (with the exception of Musta'in, who was made the plaything of rival political factions in 1412 and for six months was styled Sultan) ever exercised any function of government or enjoyed any political power.
These Caliphs were the spiritual heads only. All temporal authority lay with the Mamluk Sultans. [...] In 1412 C.E. the Caliph Al Mustain captured temporal power as well, but he could not hold such power for more than six months. The Caliphs who followed him had to remain content as spiritual heads only.