People noticed that the alcohol stored in the oak casks mellowed as time went on, spirits lost some their harshness and taking on spicy, vanilla and nutty notes and that it tasted a lot nicer, if it was left like this. So distillers started to try it with Gin, which led to the production of Aged Gins. However, even though producing Aged Gins makes the liquid have a unique and rich flavour profile, Gin producers to produce Aged Gins, meaning they aren't as common as other styles of Gin. 
Here on Ginspiration, you will find a fine selection of Aged Gins for sale from all over the world..