Since the Diaspora, some Jews have aspired to return to "Zion" and the "Land of Israel", though the amount of effort that should be spent towards such an aim was a matter of dispute. The hopes and yearnings of Jews living in exile were articulated in the Hebrew Bible, and is an important theme of the Jewish belief system. After the Jews were expelled from Spain in 1492, some communities settled in Palestine. During the 16th century, Jewish communities struck roots in the Four Holy Cities—Jerusalem, Tiberias, Hebron, and Safed—and in 1697, Rabbi Yehuda Hachasid led a group of 1,500 Jews to Jerusalem. In the second half of the 18th century, Eastern European opponents of Hasidism, known as the Perushim, settled in Palestine.
The first wave of modern Jewish migration to Ottoman-ruled Palestine, known as the First Aliyah, began in 1881, as Jews fled pogroms in Eastern Europe. Although the Zionist movement already existed in practice, Austro-Hungarian journalist Theodor Herzl is credited with founding political Zionism, a movement which sought to establish a Jewish state in the Land of Israel, by elevating the Jewish Question to the international plane. In 1896, Herzl published Der Judenstaat (The State of the Jews), offering his vision of a future Jewish state; the following year he presided over the first World Zionist Congress.
The Second Aliyah (1904–14), began after the Kishinev pogrom; some 40,000 Jews settled in Palestine, although nearly half of them left at a later point in time. Both the first and second waves of migrants were mainly Orthodox Jews, although the Second Aliyah included socialist groups who established the kibbutz movement. During World War I, British Foreign Secretary Arthur Balfour sent a letter that stated:
His Majesty's government view with favour the establishment in Palestine of a national home for the Jewish people, and will use their best endeavours to facilitate the achievement of this object,