Zara Yakob (Guèze ዘርዓ: ያዕቆብ zarʿā yāʿiqōb “Seed of Jacob”, Amharique zer' has yā' iqōb ), name of reign Kwestantinos (Ge' ez ቈስታንቲኖስ qʷastāntīnōs Constantin Ier ) born in 1399, was Négus of Ethiopia of 1434 with 1468.

Fourth wire of David Ier of Ethiopia it succeeded his/her three brothers and its three nephews after having spent 20 years with the amba of Guerchén where since the 13th century it was of use to relegate those which could have claimed with the imperial succession. From there its mystical and a little dark nature and its taste for the religious controversies.

It carried to its apogee the medieval Ethiopia. Its reign is marked by pitiless repressions against the heretics Stéphanite S and against the innumerable plotters who sought to cut down it. It did not even save its family and her children.

To the beginning of its reign, Zara Yacoub goes to Aksoum to be crowned there. During its return voyage, it founds several churches and some monasteries. It will make dig a port on the Red Sea.

Zara Yacoub sends several embassies in Occident. Of the Ethiopian monks of Jerusalem take part in the Concile of Florence in order to carry out the union of the Christians against Islam (1439 - 1441). The king Alphonse V of Aragon exchange of the letters with the Ethiopian sovereign.

In 1441, Zara Yacoub founds the monastery of Métaq in its residence of the Tégoulet (Choa), by giving him the name of the convent of Egypt from which it comes to learn the destruction. It establishes shortly after its capital and its palate more in the south, in the country of Debra-Berham (Abbey of Light).

It beats the sultan of Ifat, putting fine at the fights between Christians and Moslems in Ethiopia: the Oualashma, driven out by the predecessors of Zara Yacoub, created a new Moslem State, the Adal, whose capital is Dakar, a little in the south-east of Harrar. The sultan of Adal, Badlaï, invades the Daouaro in 1445, but is at once demolishes and killed by Zara Yacoub, which ensures peace.

Come peace, Zara Yacoub devotes its time to the propagation of the Christianity, which it imposes by the force on pagan Godjam and Damot, and with the reform of the religion at the already Christian population. It prescribes tattooings which, on the face and the arms, profess the belief in the Trinity at the same time as the renunciation of the demon. He fights against the practices of magic, codifies the obligatory festivals and the fasts. It orders the respect of Saturday, or Sabbat, which is taxed with “Judaïsme” and involves a revolt of the monks of Debra-Libanos. The opponents are punished without pity. It fights the heresies, organizes theological controversies to which it takes share in its writings: the Matshafa Berhan (Book of the Light), collection of precepts concerning the Christian discipline, the Matshafa Milad , against the Jewish and the heretics Stephanites.

Zara Yacoub dies in 1468 and is buried with the Lac Tanned, in the monastic church of the island of Dak. It leaves an empire which extends from the Baraca and Massaoua until the Ifat, to the Fatajar, in Bali. It fixed the sultan of the Hadya and preserved the States of the Sidamo, conquered until the Ouollamo by Yéshaq. His/her son Baéda-Maryam I {{er}} succeeds to him (1468 - 1478).