CREATE TABLE table_name_15 (modern_equivalent VARCHAR(255), pre_1009_province VARCHAR(255), province_of_silla VARCHAR(255))
What kind of Modern equivalent that has a Pre-1009 province of sakbang -do, and a Province of Silla of sakju?
    
SQL: SELECT modern_equivalent FROM table_name_15 WHERE pre_1009_province = "sakbang -do" AND province_of_silla = "sakju"