The rainforest is more than a million years old. It is the oldest biome. Before the last Ice Age, forests ruled the earth. Rainforests were more wide spread than they are today. It is believed that most of these plants were formed by succession. When the last Ice Age came, it covered most forests north of the equator in ice. The only vegetation that continued to grow was near the equator: the rainforests. After the last Ice Age ended some 10,000 years ago, the rainforests as we know them today remained standing.