Mount Gerizim is on the south side of the ancient city of Shechem (aka Sychar and later Neapolis). It is 3,080 feet above the Mediterranean and stands opposite Mount Ebal. The summits of these 2 mountains are close together, sheltering the city of the strategic valley below (Deuteronomy 27; Joshua 8:30-35).
At that time Joshua built an altar to the Lord, the God of Israel, on Mount Ebal, just as Moses the servant of the Lord had commanded the people of Israel, as it is written in the Book of the Law of Moses, “an altar of uncut stones, upon which no man has wielded an iron tool.”
And there, in the presence of the people of Israel, he wrote on the stones a copy ofthe law of Moses, which he had written.
And all Israel, sojourner as well as native born, with their elders and officers and their judges, stood on opposite sides of the ark before the Levitical priests who carried the ark of the covenant of the Lord, half of them in front of Mount Gerizim and half of them in front of Mount Ebal, just as Moses the servant of the Lord had commanded at the first, to bless the people of Israel. And afterward he read all the words of the law, the blessing and the curse, according to all that is written in the Book of the Law. There was not a word of all that Moses commanded that Joshua did not read before all the assembly of Israel, and the women, and the little ones, and the sojourners who lived among them. —Joshua 8:30-35 ESV
On the slopes of Mount Gerizim, the Tribe of Reuben and the tribes that were descended from the handmaids of Leah and Rachel, assembled together as per the last orders of Moses. In the valley below (the site of Shechem), Joshua read the whole law in the hearing of all the people and rewnewed the covenant of blessing on those who would obey and the curse on the disobedient.
The Jewish historian Josephus reported that Sanballat built a temple for the Samaritans on this mountain, and instituted a separate priesthood, as rivals to those of the Jews at Jerusalem. After standing for 200 years, this temple was destroyed.
It was afterwards rebuilt by Herod the Great.
For centuries Gerizim was the center of political outbreaks. The Samaritans, a small but united body, still linger here, and keep up their ancient ceremonial worship.