According to ancient tradition passing from generation to generation, the Horowitz family originated from a dynasty of well-known Spanish and French rabbis and scholars: R. Yitzhak Ha-Levi of Gerona, the son of R. Pinchas Ha-Levi, the brother of famous HaROeH (R. Aharon Ha-Levi) of Barcelona, the son of R. Yosef Ha-Levi, the son of R. Banbaneshti Ha-Levi, the son of R. Yosef Ha-Levi, the son of R. Zerakhyah Ha-Levi, the author of "Ha-Maor", the son of R. Yitzhak Ha-Levi of Gerona, the son of R. Zerakhyah Ha-Levi, the son of R. Shem-Tov Ha-Levi, whose roots, in turn, can be traced back to the prophet Shmuel and the descendants of Yitzhar, the son of Khat, the son of Yakov our Father.
And the legend tells as how at the height of anti-Jewish persecutions in medieval Spain "there stood up a man of that high and noble family, took his wife and his children and went to Eretz Chana'an (pioneers of the Exodus from Spain used this name to refer to Bohemia). And they came to Eretz Chana'an".
In that period Vladislas II, the eldest son of Casimir IV Jagiello, King of Poland, reigned in Bohemia (from 1471). After the death of Hungarian king Matthias Corvinus in 1490, Vladislas was elected King of Hungary (under the name of Uláº¬ó ‰‰) and since then spend most of his time in Buda (modern Budapest). So did his son, Louis, the last Jagiellonian king of Bohemia and Hungary who inherited the throne (under the name of Ludvik II and Lajos II) at the age of 9 after his father's death in 1516. Louis drowned fleeing the battlefield after his army was defeated by Ottoman Turks at Mohᣳ on the Danube in 1526. The reign of the two Jagiellonians was marked by a decline of royal authority. In this latter period the Catholic lords gained entrance to the royal court and exercised strong influence on the public affairs of Bohemia which was devastated by incessant wars and conflicts and needed people of skills and means. On the other hand, the Catholic church's influence was weakened by the Hussite wars and the struggle waged against it by alternative Christian movements. Under these conditions Jews were permitted to stay there, and they could easily find a place to settle.
The miserable wanderer was a wealthy man. He settled in a village (some sources say that he simply purchased it), which later became a town named Horovice (Horowitz, about 50 km southwest of Prague). This man's name was Yishayahu ben Moshe Ha-Levi, and, later, after he moved to Prague and assumed an important position in its Jewish community, he was called "Yishayahu Ha-Levi Ish Horowitz" - the man of Horowitz, after the name of the place from where he had come. He purchased a big house on "Gold Street" in the Jewish Town of Prague, where jewelers, merchants and other wealthy representatives of the Jewish population then lived.