Dantien is a point as well as a region, and the more we advance the more important it is to locate this point with accuracy. It is a place of vigilance and readiness as well as quiet. In dwelling there the mind cannot settle into itself and think. To locate the dantien breathe in strongly through a tiny hole you make with the lips. The centre of the tension you feel in the lower belly is the dantien. If you don't feel tension then the hole is not small enough. I use this technique throughout the day to bring my attention regularly back to the dantien, and thereby to my own sobriety and probity.