Linked from
The 42 pages that link to Islamic calendar, each with the reason it gives.
Lunar calendarBroader topic: It is a prominent example of a calendar that remains purely lunar.
CalendarBroader topic: Its months follow lunar phases without intercalation to track the seasons.
Lunar phaseBroader topic: Month beginnings are traditionally tied to sighting the new crescent.
New moonBroader topic: The visibility of the new crescent helps determine the start of each month.
Solar calendarBroader topic: Its months move through the seasons, unlike those of a solar calendar.