Answer:
Japanese smiths traditionally use tama-hagane, steel produced in a tatara smelter from iron-rich sand. Modern smiths making Japanese katana's in the traditional manner still use this type of steel today, now produced in the last operating tatara smelter, located in Yokota, Shimane Prefecture.
while chinese had crucible steel used in the Chinese swords, called chi-kang (combined steel), was similar to pattern welding, and edges of it were often forge welded to a back of soft iron, or jou thieh.