The Neogene Period is a geological time frame that lasted from about 23 million to 2.6 million years ago. It is divided into two epochs: the Miocene and the Pliocene. During this period, the Earth's climate became cooler and drier, leading to the expansion of grasslands and the evolution of many modern plant and animal species. This era saw significant developments in mammal and bird evolution, with the rise of large mammals like mammoths and saber-toothed cats. The Neogene Period also marked the formation of the Himalayas and other mountain ranges due to tectonic activity, shaping the planet's geography and ecosystems.