The “triennial cycle” was the practice of Jews in Eretz Yisrael, which works by dividing the Torah into weekly sections, roughly a third of the length of a Babylonian weekly parsha, which, if you follow it week by week, means you end up finishing in something like three and a half years. The revived triennial cycle is now on its second run ב”ה with Jews around the world learning according to it.
The Triennial Cycle is now hosted at Mekor Mayim Hayyim.
Resources
Suggested aliyot divisions for Bereshit
