sentences:  When in 331 BC Zopyrion, Alexander's viceroy in Thrace, "not wishing to sit idle", invaded Scythia and besieged Pontic Olbia, he suffered a crushing defeat at the hands of the Scythians and lost his life.The fall of the Second Scythian Kingdom came about in the second half of the 3rd century BC under the onslaught of Celts and Thracians from the west and of Sarmatians from the east.With their increased forces, the Sarmatians devastated significant parts of Scythia and, "annihilating the defeated, transformed a larger part of the country into a desert".