Back in the day:
Bouts are 10 minutes in length, with 2 three-minute extra (overtime) periods if no winner is determined in regulation. Both extra periods shall start in the “referee’s position”.
If a takedown occurs in the first 2 minutes of the bout, it shall become a continuous 10-minute bout.
If no takedown or fall occurs in the first 2 minutes, the remaining 8 minutes are divided into two 4-minute periods, with each wrestler starting on top in one period.
If a wrestler scores a fall in the first 4-minute period, this terminates only the first 4-minute period. The other wrestler has the opportunity to score a fall in a faster time in the second 4-minute period.
Consolation bouts consist of three 2-minute periods. A referee can call for extra periods if he is unable to declare a winner in regulation.
Any part of both shoulders held in contact with the mat for an appreciable length of time (i.e., 3 seconds) constitutes a fall.
If no fall has resulted after the end of the regular period of wrestling, the referee shall award the bout to the wrestler who shows greater wrestling ability and aggressiveness, provided the wrestler has a riding time-advantage of at least one-minute.
The one-minute riding time advantage is not necessary to declare a winner in extra periods or consolation bouts.