Young Israeli Girl

The first large wave of "modern" immigration, known as the First Aliyah, began in 1881, as Jews fled pogroms in Eastern Europe. Although the Zionist movement already existed in theory, 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 state; the following year he presided over the first World Zionist Congress.
The Second Aliyah (1904–1914), began after the Kishinev pogrom; some 40,000 Jews settled in Palestine, but nearly half of them left. Both the first and second waves of migrants were mainly Orthodox Jews, but those in the Second Aliyah included socialist pioneers who established the kibbutz movement. During World War I, British Foreign Secretary Arthur Balfour issued what became known as the Balfour Declaration, which "viewed with favour the establishment in Palestine of a national home for the Jewish people". At the request of Edwin Samuel Montagu and Lord Curzon, a line was also inserted stating "it being clearly understood that nothing shall be done which may prejudice the civil and religious rights of existing non-Jewish communities in Palestine, or the rights and political status enjoyed by Jews in any other country".
The Jewish Legion, a group of battalions composed primarily of Zionist volunteers, assisted in the British conquest of Palestine. Arab opposition to the plan led to the 1920 Palestine riots and the formation of the Jewish organization known as the Haganah (meaning "The Defense" in Hebrew), from which the Irgun and Lehi paramilitary groups split off. In 1922, the League of Nations granted the United Kingdom a mandate over Palestine under terms similar to the Balfour Declaration. The population of the area at that time was predominantly Arab and Muslim, with Jews accounting for about 11% of the population.