Historically, Poland has been part of the barrier against the steppe invassions, first the Mongols, then the Russians themselves. From that point of view, it would be central Europe, as the steppe peoples would be eastern Europe. Poles often lived within the HRE, which would place them squarely in the Mittel-europa.
The Cambrian Explosion refers to the metaphorical explosion of life that began 542 million years ago and lasted for roughly 40 million years. This lesson will cover the events that occurred during this time period.
The Cambrian explosion or Cambrian radiation was the event of approximately in the Cambrian period when most major animal phyla appeared in the fossil record. It resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversification of other organisms.