The European countries tasked with the drawing of new borders for middle Eastern Countries were France & Great Britain.
The borders for the Middle Eastern countries was drawn in 1916 by Tatton Benvenuto Mark Sykes(Great Britain) and François Marie Denis Georges-Picot(France)
It should be noted however that both nations, i.e France and Great Britain, were not exactly concerned about ethnic or religious difference when the borders were being drawn, rather
They were more concerned about controlling the area because they knew about the oil presence and knew whoever controlled it, controlled profits from the oil.
The main reason Australia's economy collapsed right before the Great Depression began is because the government made poor decisions. Many factors led to their economy collapsing but they can be summed up by the government made poor decisions.