1. Mesopotamia or the Hilly Flanks, the area also sometimes called the Levant, first concentrated into major population centers around the Tigris, Euphrates, and Nile river valleys.
2. China, first concentrated around the Yangtze and Yellow river valleys and Pearl river delta.
3. India/Pakistan, first concentrated around the Indus river valley.
4. Mexico (Olmecs, Aztecs) and Peru (Incas)
The Mesopotamian civilization got the earliest start and had grown and expanded the most by 1 AD. The Mesopotamian/Western core had also shifted westward by this time. First to Greece, and then to Rome. The Greeks conquered and Hellenized the entire ancient world from Eastern Europe (Serbia) to Central and Southern Asia (Afghanistan, India). The Greeks, Phoenicians and Romans colonized all of southern Europe and the coastline of the Mediterranean.
step two: knowing that Western Civ got a head start and had spread more by this time, and also that its core had shifted multiple times, also guess every large and/or hospitable country on or around the areas Western Civ had colonized or moved to (Greece, Iran, Turkey, Italy, everywhere from Spain to Afghanistan). Also guess the countries immediately peripheral to the two other older cores (Bangladesh, Japan).
That leaves only Nigeria. Some anthropologists have speculated that Nigeria may have also been another cradle of civilization where civilization developed independent of the other cores. If you knew that you could guess it. If you didn't, then just guessing the largest most populous countries today would have got you the answer soon enough.