The etymology of ''Bangladesh'' (Country of Bengal) can be traced to the early 20th century, when Bengali patriotic songs, such as ''Namo Namo Namo Bangladesh Momo'' by Kazi Nazrul Islam and ''Aaji Bangladesher Hridoy'' by Rabindranath Tagore, used the term. The term ''Bangladesh'' was often written as two words, ''Bangla Desh'', in the past. Starting in the 1950s, Bengali nationalists used the term in political rallies in East Pakistan. The term ''Bangla'' is a major name for both the Bengal region and the Bengali language. The origins of the term ''Bangla'' are unclear, with theories pointing to a Bronze Age proto-Dravidian tribe, the Austric word "Bonga" (Sun god), and the Iron Age Vanga Kingdom. The earliest known usage of the term is the Nesari plate in 805 AD. The term ''Vangaladesa'' is found in 11th-century South Indian records. The term gained official status during the Sultanate of Bengal in the 14th century. Shamsuddin Ilyas Shah proclaimed himself as the first "Shah of Bangala" in 1342. The word ''Bangla'' became the most common name for the region during the Islamic period. The Portuguese referred to the region as ''Bengala'' in the 16th century. 16th-century historian Abu'l-Fazl ibn Mubarak mentions in his ''Ain-i-Akbari'' that the addition of the suffix ''"al"'' came from the fact that the ancient rajahs of the land raised mounds of earth 10 feet high and 20 in breadth in lowlands at the foot of the hills which were called "al". This is also mentioned in Ghulam Husain Salim's Riyaz-us-Salatin. The Indo-Aryan suffix ''Desh'' is derived from the Sanskrit word ''deśha'', which means "land" or "country". Hence, the name ''Bangladesh'' means "Land of Bengal" or "Country of Bengal".