region around the imperial capital, outskirts
甸 refers to the area surrounding an imperial capital, the outskirts or suburban region directly governed by the central authority.
甸 combines 勹 (wrap, enclose) with 田 (field), suggesting enclosed fields or territory around a capital. The exact historical development is uncertain, but the component combination fits the meaning of a defined administrative region.
Picture a wrapped (勹) field (田) just outside the city walls: this enclosed farmland is the outskirts, the region around the imperial capital.
For デン, imagine a den (デン) of officials managing the enclosed fields around the capital: den -> デン, the administrative outskirts.
Burma