The old town of Aden is situated in the crater of an extinct volcano. Legend has it that Cain and Abel are buried somewhere in the city. It has long been at the centre of trade between India, Europe, Africa and China and was known as Eudaemon (blissful, prosperous) in Ancient Greek. At times, it has been occupied by the Portuguese, Ottomans and the British. In 1850, it was declared a free trade port focusing on liquor, salt, arms, opium and coffee. Yemen has been in a state of political crisis since 2011 and lies 7th on the Fragile State Index.