The Baliem Valley extends on more than 37mi (60km) long and about 12mi (20km) wide in the heart of the high mountains and impenetrable forests of central Papua. With no road or river connection to the rest of the province, it is only accessible by plane. Oscillating between 4,593 and 6,561ft (1,400-2,000m) above sea level, it is full of rivers and fertile farmland on the mountainside where the very isolated local tribes grow sweet potatoes and other vegetables.