Tricennium

As early as the second decade after his entry into Italy Theodoric made all illegal or irregular acquisitions that had taken place prior to this fixed date [28 August 489] subject to the thirty-year statue of limitation (tricennium).

With a site I have been working with in Iceland, I am dealing with 30-year time units or tricennia, and even if it is no Pompeii, there are still features that we know represented much shorter time scales—the construction of a fireplace that could have been accomplished in a day, the placing of a coin under a timber sill beam that only took a few seconds.