Question: When hittite middle kingdom , new kingdom of egypt is the ubaid period in mesopotamia how many early chalcolithics are there?
Schema: create table table_23537091_1 (early_chalcolithic varchar, ubaid_period_in_mesopotamia varchar, PRIMARY KEY (early_chalcolithic))
SQL: select count(early_chalcolithic) from table_23537091_1 where ubaid_period_in_mesopotamia = "hittite middle kingdom , new kingdom of egypt"