The Islam emerged in the sixth century AD, and with it, the first Islamic states started to occur. The Islamic states started to occur because this religion managed to unite lot of tribes and create one powerful entity. The military strength was big, so it was used for expansion, and on the territories that were conquered, the people were converted to Islam, very often forcefully. This has resulted in rapid change of the political and religious map of the world, with a very large area becoming dominated by Islam. The Islamic states, once properly established, flourished and were very advanced, having big achievements in numerous scientific fields. Unfortunately, the fundamentalist fraction managed to prevail over time and stopped the progress, so gradually the Islamic states started to fall behind the other parts of the world when it came to development, and that can be seen even nowadays.
The Earth also gives us clues about the levels of greenhouse gases that existed in the past. For example, ancient air bubbles trapped deep in the ice of Greenland and Antarctica reveal how much carbon dioxide was present long ago.
