Era beginning/end
Though out the 7th and 8th century first of the central power systems begin to go off line as the ability to process fuel is hampered. power generation become distributed or powered down.
Most cities had constructed advanced power stations or retro fitted lifters to power their cities. The dark mater fuel in these systems began to run out and with no knowledge of how to make more. Reliance on distributed power systems like solar Geo-magnetic, or no power at all. cities that wouldn't adapt to low power were abandoned. Wars over resources were common in this era. Alterra lacks coal and oil so those simpler power sources were not available, and the settlers lacked the knowledge on how to build fusion fission or anti-mater based central power systems.