Actually there is a Somali calendar, but not in use.Cuz somalis never kept nor write it history and identity also language and culture even somalis don't have Somali calender
The Somali calendar (Somali: Soomaali tiro ammin) is based on both the solar and lunar calendar systems. The Somali solar calendar is known as Amin-tiris or Shin-tiris while the lunar calendar was known as Dayax-tiris.
Structure
Besides the weekly cycle, there are four other major cycles in the system: the 50-day cycle, which is 7 weeks + 1 day; the yearly cycle which is 7 x 50 days plus 15 days; the seven-year cycle which is 7 x 365 or 2,555 days long; and the 49-year cycle which is 7 x 7 years in length. All these time units share the number of seven or weekly cycle. Every unit is named after its first day, which is also the last day of yearly and 50-day cycles.
For further reads >> https://en.wikipedia.org/wiki/Somali_calendar