Most major import markets require goods to carry a country-of-origin marking, legible and in a location a normal buyer would see before purchase. The specific wording, placement and size requirements differ by market — US rules under the Tariff Act are notably strict about permanence and legibility, while other markets are comparatively more flexible on format but still require the marking to exist.
The marking requirement sits on the product or its immediate packaging, separate from the customs declaration itself. A shipment can have perfectly accurate customs paperwork declaring Chinese origin and still face a hold at destination if the physical goods are not marked, because the two checks — declared origin and physical marking — are verified independently.
Products assembled or finished partly in China from components sourced elsewhere raise a harder question: substantial transformation rules determine which country's origin actually applies, and that determination can affect both the marking requirement and the tariff treatment, including anti-dumping exposure on some product categories.
For a new product line, the practical check is confirming the destination market's specific marking format before finalizing packaging artwork — a missing or incorrectly worded origin mark is one of the more avoidable reasons for a customs hold.