Britain wanted to counter France and Russia's growing influence in the Middle-East as far back as ca. mid 1800s by supporting and encouraging the emigration of Jews to Palestine and posing themselves as their protectors. It didn't really work out. Still the first big zionist immigration (about 35,000 Jews, 3% of the european jewish population) wave to Palestine in 1882, due to the pogroms in the Russian Empire, already stirred some tensions whithin the Ottoman Empire which began to restrict it while simultanueously giving Jews the same right to buy land as the Arabs. There's been a second wave (35-40,000 Jews), largely for the same reasons as the first, about 20 years later. This one didn't last however, due to the lack of industry, poor living conditions and the hostility of the local populations. It is estimated that between 50 to 90% of these immigrants ultimately left Palestine.
The Ottoman Empire at the beginning of the 20th century was on its last legs. It suffered from a massive lack of technological and industrial development compared to the european counterparts, losing territories and internal political dissensions and corruption were rife. Arab and Palestinian nationalisms were on the rise and opposed to a mass jewish emigration to Palestine. The Ottomans siding with Germany in WWI sealed their fate and the region's. The Arab revolts against the Ottomans were encouraged during the War by Britain, for obvious reasons. After WWI the Empire was dismantled in 1920 (Treaty of Sèvres) giving birth to new countries in this region, many of which had borders largely drawn according to the interests of the colonial powers and not the living populations, ethnic groups, religions and or the historical context.
Add to that the Balfour declaration in 1917, ironically named after the man who made his opposition to a mass emigration of Jews fleeing Russia into Britain one the main themes of his election campaign in 1906, which announced the creation of "National Home for the Jewish People" in Palestine (the wording here is very interesting). All the ingredients for the current situation in the Middle-East were were already there.
