If I remember correctly the Aztec “calendar round” included 2 cycles, one the standard year and I think the other was the Venus year. They probably got it from the Mayans. Jews also celebrate a 50 year jubilee year I think when debts are forgiven. Some West African cultures also throw out old wood carvings every 50 years and carve new ones. I new of an American black man who bought a large number of these cast off carvings and had them displayed publicly. Unfortunately the building was burned and all lost.
The 50 year cycle (which is also give as 52 year cycle) was looked at ahead of the 50th anniversary of the 1929 stock market crash.