1991. Although its fall lapsed somewhat into 1992, as well.
Fine soil found on the bottom of rivers is called silt.
Answer:
The Germans used mustard gas for the first time during war in 1917. They outfitted artillery shells and grenades with mustard gas that they fired in the vicinity of the troop target.
Shang dynasty was the reputed successor to the quasi-legendary first dynasty, the Xia