Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean. About 250 million years ago, during the Triassic, a new ocean began forming in the southern end of the Paleo-Tethys Ocean. A rift formed along the northern continental shelf of Southern Pangaea (Gondwana). Over the next 60 million years, that piece of shelf, known as Cimmeria, traveled north, pushing the floor of the Paleo-Tethys Ocean under the eastern end of Northern Pangaea (Laurasia). The Tethys Ocean formed between Cimmeria and Gondwana, directly over where the Paleo-Tethys used to be. During the Jurassic Period (150 Ma), Cimmeria finally collided with Laurasia. There it stalled, the ocean floor behind it buckling under, forming the Tethyan Trench.