Why is it that Orthodox fast for 56 days, and not just the 40 days of Lent that Roman Catholics observe?

In our Ethiopian Church of the Kingdom of God, the 16 (actually 15, the last Sunday being Resurrection Day) fasting days over and above the 40 days of Lent, resulted from the additional 2 weeks that are placed at the beginning and at the end of the long period respectively.

We, Ethiopians, fast the first week, named "the Fast of H'rqal (Heraclius)" in commemoration of the Roman Emperor of the 7th century who responded to the call of Christians of Jerusalem for deliverance from the infidel invaders by rescuing them from the latter with his conquering forces. For Ethiopians, Jerusalem has special significance, as they inhabited it as pioneers from the time of its founder and their ancestor Melke-Zedeq to this day.

As to the last week, named "H'mamat (Passion)", Ethiopians fast it separately but in conjunction with Lent in commemoration of the Passion of Christ. Throughout its duration, they confine themselves in the Churches in spirited meditation and contrition along with the continuous prayer and prostration.