The depalatalization of consonants preceding e and ä took place later, thus the frequency of occurrence of palatalized consonants was lowered, but it strengthened the palatalization contrast at the same time. The change of ’ä > ě and ä > a took place at the end of the 12th century.
Later, the depalatalization of consonants preceding e and ä occurred, reducing the frequency of palatalized consonants but strengthening the contrast in palatalization. By the end of the 12th century, there was a change from ’ä to ě and ä to a.