Simply, they united because coming together would be the only way to defeat Persia, or else they would lose separately. Hopefully this helped!
True ,Early humans were able to move out Asia into North America during an Ice Age because of a land bridge.
either A or D sorry i know this may not help but hopefully it narrows it down.
the basis for my answer is Roman Catholics believed that they could only go to heaven with like say 3 sins, and if they have 4 and need to get rid of one or to or all 4 even then they would pay the pope and they would supposebly be freed from that sin, so i do beleive both A and D apply to that.
The First Crusade resulted in the successful conquest of Jerusalem and the establishment of a few tenuous Crusader states.
In response to the fall of these Crusader states, the second crusade was called in response in order to recapture the areas in question. However, it was a complete failure.
The Third Crusade was called in response to the fall of Jerusalem to Saladin and increasing Muslim successes in the Holy Land. However, the crusade immediately ran into problems, with leaders dying, returning home, and being unable to move inland. Ultimately the Third Crusade ended with a negotiated peace in which Christian pilgrims were given access to Jerusalem.
Pope Innocent III initiated the Fourth Crusade, which immediately went off of the rails, with the crusaders getting involved in Venetian-Byzantine politics, fighting Christians, and eventually sacking Constantinople without ever reaching the Holy Land.
