Complex sentence: Because Brighton Beach's original Russian-speaking population arrived in the 1940s and' 50s and were primarily Jews from Odessa, Ukraine, Brighton Beach became known as "Little Odessa," and later "Little Russia".
Split into simpler sentences: Because Brighton Beach's original Russian-speaking population arrived in the 1940s and' 50s and were primarily Jews from Odessa, Ukraine, Brighton Beach is sometimes known as "Little Odessa". During this time, Brighton Beach came to be known as "Little Odessa" and later "Little Russia".