Simplify the following text for a Grade 10 native English-speaking person.
Original: Both Ebara Ward and Shinagawa Ward had been created in 1932 , with the outward expansion of the municipal boundaries of the Tokyo City following the 1923 Great KantÅ Earthquake .
Simplified: Both Ebara Ward and Shinagawa Ward had been created in 1932 when Tokyo City expanded after the 1923 Great KantÅ Earthquake .