After the abolishment of postal system in the latter half of 1970s by the Khmer Rouge, in 1980 Cambodia issued postage stamps for use again under the new Vietnamese backed regime. Yet due to financial difficulties, only two stamp sets were issued in three years. A change came when in 1983 Coprefil, the Cuban state owned enterprise started its philatelic contract with the Phnom Penh authority, since then stamps were regularly issued again.
Following Cambodia's absence from the philatelic scene for several years, Coprefil had to find an efficient way to reintroduce the country to dealers and collectors worldwide, for maximum exposure nothing was better than participating in international stamp exhibitions.
The first Cambodian stamp prepared by Coprefil to celebrate an international stamp exhibition was issued in 1984 (click here for my relevant blog post), but before it the company had participated in international philatelic events on behalf of Cambodia. One of the early examples is the Sindelfingen International Stamp Fair in Germany, 1983. The cover shown below is a self made souvenir of the fair.
The Sindelfingen International Stamp Fair is an annual event held in Sindelfingen of Baden-Württemberg, Germany since 1983. Stamps and the commemorative cachets of Cambodia, Cuba, Laos, Nicaragua and Vietnam are featured on this cover. The five countries were clients of Coprefil at that time.
Cachets of Cuba and Nicaragua are in Spanish. Coprefil certainly knows that Cambodia, Laos and Vietnam are francophone, however the cachets of the trio are in German. It is likely that the Cuban company was actually represented by a German agency which also prepared the cachets.
The following is a close up of the Cambodian cachet which ties the 1983 "Butterflies" 0.5r stamp (Sc#387) :
This may be one of the earliest post-1979 Cambodian cachets to mark philatelic events, if not the first. Contemporary cachets of Cambodia are poorly documented, it posts great challenge for serious collectors to collect and study them.