[muawiyah]

Rome relinquished formal government control over Brittain over 100 years BEFORE the beginning of the Dark Ages.

However, with the cessation of foreign trade (and the rise of Channel pirates), the gold and silver was simply buried because it had little internal use where direct trade was very common.

[Antoninus]

However, with the cessation of foreign trade (and the rise of Channel pirates), the gold and silver was simply buried because it had little internal use where direct trade was very common.

Doubtful. When Honorius withdrew the last legions from Britain, it most likely gave a green light to complete lawlessness and a general breakdown of order. The various hordes were most likely buried by those trying to prevent it from being forcibly taken. Those who buried it then most likely perished before it could before it could be recovered.