The most important innovation in termite control since the 1950's is termite baiting. This new technology promises to replace the old liquid barrier treatments. The drawbacks to barrier treatments are you can't always form a continuous barrier and termites can invade through any gaps in the treatment.
Pesticides can deteriorate, leaving termites entry through weak spots.
If the soil is disturbed or washed away, another opportunity presents itself to termites. Most importantly, the termites haven't gone anywhere, they are still in the yard randomly foraging around your home searching for gaps to penetrate. Baiting works by placing interception stations in the soil around your home. As termites forage, they find the stations and start to feed. Once feeding begins, a small amount of slow acting toxicant is added to the station.