Since ancient times, people have opened the rainforest, altered the ecosystem, shaped the landscapes and created rice paddy and terraces to support the growing population. Javan rice terraces have existed for more than a millennium and had supported ancient agricultural kingdoms. The growing human population has put severe pressure on Java's wildlife, as rainforests were diminished and confined to highland slopes or isolated peninsulas. Some of Java's endemic species are now critically endangered, with some already extinct; Java used to have Javan tigers and Javan elephants, but both have been rendered extinct. Today, several national parks exist in Java that protect the remnants of its fragile wildlife, such as Ujung Kulon, Mount Halimun-Salak, Gede Pangrango, Baluran, Meru Betiri, Bromo Tengger Semeru and Alas Purwo.