Diminishing the territory was a type of punishment imposed on samurai including daimyo (Japanese feudal lord) and hatamoto (direct vassal of the shogun) during the Edo period, that deprived samurai of their ranks, and partially diminished their territories, castles, and residences.
減封（げんぽう）とは、江戸時代においては大名、旗本などの武士に課せられた刑罰を意味し、武士の身分を剥奪して所領と城・屋敷の一部を削減することをいう。