While (and before) Phoenicians were colonising the Mediterranean, our most adventurous ancestors were heading far east. Micronesian colonists arrived in the Marshall islands around 2000 BC while the Old World was being dominated by the Egyptians and Babylonians. The world population reached around 50 million towards 1000 BC. The Marshallese used stick charts to navigate their way between the c. 2,100 islands in the Micronesia region. The European age of discovery was about 3,500 years later with Spain claiming the islands in 1592, and other European powers recognising that sovereignty in 1874. The islands get their name from a British explorer who visited in 1788. Spain sold the islands to the German Empire in 1885. The United States conquered the islands in 1944 and began testing of Nuclear bombs on the Bikini Atoll in 1946. The Bikini is named after these islands because of the 'explosive effect' of the garment. The Marshall islands gained self-government from the US in 1979, signing a Compact of Free Association in 1986.