Complex sentence: On April 30,1948, the property became a State Park and in December of 1949, the Park was ceded to the City of Oakland with the proviso that Knowland Park always remain a public park.
Split into simpler sentences: On April 30 1948, the property became a State Park. In December 1949, the park was leased to the City of Oakland with the proviso that Knowland Park would always remain a public park.