Zionist Congress in Basel in 1901. In its early years, the organization was headed by the Jewish industrialist Johann Kremenezky. Early land purchases were completed in Judea and the Lower Galilee. In 1909, the JNF played a central role in the founding of Tel Aviv. The establishment of the “Olive Tree Fund” marked the beginning of Diaspora support of afforestation efforts. The JNF collection boxes or Blue Box (known in Yiddish as a pushke) has been part of the JNF since its inception, symbolizing the partnership between Israel and the Diaspora. In the period between the two world wars, about one million of these blue and white tin collection boxes could be found in Jewish homes throughout the world. From 1902 until the late 1940s, the JNF sold JNF stamps to raise money. For a brief period in May 1948, JNF stamps were used as postage stamps during the transition from Palestine to Israel. Ottoman era The first parcel of land, east of Hadera, was received as a gift from the Russian Zionist leader Isaac Leib Goldberg of Vilnius, in 1903. It became an olive grove. In 1904 and 1905, the JNF purchased land plots near the Sea of Galilee and at Ben Shemen. In 1921, JNF land holdings reached 25,000 acres (100 km²), rising to 50,000 acres (200 km²) by 1927. At the end of 1935, JNF held 89,500 acres (362 km²) of land housing 108 Jewish communities. British Mandate In 1939, 10% of the Jewish population of the British Mandate of Palestine lived on JNF land. JNF holdings by the end of the British Mandate period amounted to 936 km². By 1948, the JNF owned 54% of the land held by Jews in the region, or a bit less than 4% of the land in what was then known as the British Mandate of Palestine. By the eve of statehood, the JNF had acquired a total of of land; another had been acquired by other Jewish organizations or individuals. Most of the JNF's activities during the Mandatory period were closely associated with Yossef Weitz, the head of its settlement department. From the beginning, JNF's policy was to lease land long-term rather than sell it. In its charter, the JNF states: "Since the first land purchase in Eretz Israel in the early 1900s for and on behalf of the Jewish People, JNF has served as the Jewish People's trustee