Coriander contains antioxidants, which means, food will not go rancid, when this spice is used. It has many medicinal benefits as well, such as treatment for type 2 diabetes. In traditional indian medicine it is used as a diuretic, whereby, you boil equal amount of dhania seeds & cumin seeds with water and consume the liquid.
The plant is said to have been cultivated in Greece, for the manufacture of perfumes. It was then discovered for it's use as a spice and a herb for flavouring.
More info: http://en.wikipedia.org/wiki/Coriander
Products can last up to 2 years, provided they are stored in a cool place within an airtight container.