What happened around 1200 bce to mycenaeans, minoans, hittites, and (partially) egypt?

The suggested civilizations and countries have all experienced either decline or the end of their civilizations in the given time period.

Around the year 1200 BC the Minoan and Mycenaean civilizations on the islands of the Aegean Sea stopped existing after a long time of prosper and advancement in their societies. The reasons are not totally clear about this, but the most likely seem to be a systematic invasion from mainland Greece, strong volcanic eruptions, earthquakes, and even a tsunami.

The Hittites, at the central and eastern part of modern day Turkey, were also by the end of their civilization at this period after a slow decline, and the once strong military kingdom stopped existing. The reasons suggested are internal problems and lack of food after continuous period of droughts that was ruining the crops.

The Egyptians, unlike the previous ones, did not stopped existing, but were on a decline in this period and were facing a big crisis, both with keeping the people in order in the empire and financially, and this marked the slow decline of Egypt which still managed to survive for almost 900 years more but as a pale shadow of the glorious empires from the past.

b)

it created free trade throughout the colonial territories.