Simplify the following text for a Grade 11 native English-speaking person.
Original: After the collapse of the Central Powers in November 1918 , the local commander of the Ober-Ost signed an agreement with the Temporary Council of the SuwaÅ ki Region and de facto allowed for the region to be incorporated into Poland .
Simplified: After the end of the Central Powers in November 1918 , the commander signed an agreement with the Temporary Council of the SuwaÅ ki Region and let the city back into Poland .