Why was mass production the more important reason the 1920s economic boom was sustained?

they chose sides following the death of the islamic prophet muhammad in ad 632. a dispute over succession to islamic prophet muhammad as a caliph of the islamic community spread across various parts of the world, which led to the battle of jamal and battle of siffin.

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climate change is the big reason to the decline of the indus valley which also caused floods. so i dont know what answer would best fit the description thats just what i found online! have an awesome