Historically there was no clearly defined boundary in this part of the Arabian peninsula; at the start of the 20th century the Ottoman Empire controlled what is now Iraq and Britain controlled Kuwait as a protectorate.[2] Britain and the Ottoman Empire theoretically divided their realms of influence via the so-called 'Blue' and 'Violet lines' in 1913-14, by which the Ottomans recognised British claims on Kuwait, divided from Ottoman Mesopotamia along the Wadi Al-Batin (the so-called 'green line', see map right).[3][4][5]