Complex sentence: The Republic of West Papua is a proposed but unrecognised separatist state in the Western New Guinea region (comprising the provinces of Papua and West Papua) that was unilaterally declared during the temporary United Nations administration of the region in 1963.
Split into simpler sentences: The Republic of West Papua is a separatist-proposed but internationally unrecognised state in the Western New Guinea region (comprising the provinces of Papua and West Papua). It was unilaterally declared during the temporary United Nations administration of the region in 1963.