Paleogeographical considerations on the development of the Paratethys and the Mediterranean during Oligocene and Miocene are presented in twelve time-slices. Plate tectonic activities and the collision of India with Asia caused the destruction of the Western Tethys Ocean in the Late Eocene. The Mediterranean and the intracontinental Paratethys basins came into existence as new marine realms. In the Mediterranean Basin open oceanic connections existed throughout the Oligocene and most of the Miocene. The Eastern Paratethys and the Central to Western Paratethys showed different marine conditions and changing connections most of the time. A first period with reduced salinity, anoxic bottom conditions, and strong endemisms occurred throughout the Paratethys in a short period of the Lower Oligocene (Solenovian, NP 23). It was followed by more open marine conditions with wide-spread clastic sedimentation (Upper Kiscellian, Kalmykian, NP 24). By the collision of Africa and Arabia with Eurasia, the seaway between the Mediterranean Sea and the Indian Ocean was closed in Burdigalian time, but a new landbridge enabled a distinct mammal migration between the continents (Gomphotherium Landbridge). During the Middle Miocene marine seaways between the Indian Ocean, the Mediterranean, and the Paratethys opened and closed intermittently. Finally, the marine connections of the Paratethys were strongly reduced, and gave way to the endemic faunal development during the later Miocene (Sarmatian to Pontian).