In Syria there is evidence that shows toxic gas used 1,700 years ago . There is said to be residue of yellow sulfur crystals inside of a jar found next to a pile of dead bodies that were found. this discovery is important for many different reasons . One reason is because of the problem happening in Syria now.reason why this discovery is important is because it helps us understand how the people of that time lived. You can tell the people were really violent and weren't new to war , you can tell all this by seeing that they used chemical weapons.
http://news.discovery.com/history/archaeology/toxic-gas-brought-death-in-syria-more-than-1700-years-ago-130904.htm
