title_body: Why have distinct styles of Scotch clustered in different regions of Scotland?
upvoted_answer: Much of it has to do with the material they used to dry the grain. If the distillery traditionally used peat (because it worked well, was widely available, and cheap, the smell made its way into the spirits (this is why the Islay area has such a concentration of “peaty” whiskies. 
  
  Much of the flavor and color comes from how the distillery ages the whisky. One of the casks of choice these days is American white oak. Bourbon distillers in the US are only allowed to use a cask once. Scotland distilleries will buy the used casks and reuse them several more times. The best whiskies tend to be aged 12 or more years in ex-bourbon casks (first run of whisky).