Simplify the following text for a Grade 11 native English-speaking person.
Original: Ultimate reasons for these migrations could include drought , developments in warfare\/weaponry , earthquakes or other natural disasters , meaning that the Migrations theory is not necessarily incompatible with the other theories mentioned here .
Simplified: Ultimate reasons for these migrations could include drought , developments in warfare\/weaponry , earthquakes or other natural disasters . This means that the migrations theory is not incompatible with the other theories mentioned here .