The prohibited act is unlawful movement across the border. It does not require a sale, a profit, or an intention to supply anyone. Carrying a substance in luggage, on the body, in a vehicle or sending it by post all fall within the article, and so does receiving an international parcel where the receipt forms part of the movement.
Quantity drives the part, using the same Government thresholds as Article 228. Aggravating features — a group acting in concert, use of an official position, concealment from customs control by special means — move a case up.
Article 229.1 frequently sits alongside Article 228 or 228.1 on the same facts: one article for bringing the substance in, another for possessing or supplying it afterwards. Whether that is a genuine multiplicity or double-counting of a single act is a live defence question.