As a matter of fact, forgeries were already under way as the main patrons of these masters were rich ruling dynasties, princes, dukes and other noble families as well as merchants and bankers who would pay huge sums of money to acquire their best works and some unscrupulous dealers took advantage of a growing demand from these customers to provide them with forgeries, notably drawings.
Some of these masters and certain collectors even wanted to keep some of the pieces they most treasured and instead of turning down certain requests made by their customers they did not hesitate to trick them in supplying copies. This happened with the Count of Cantecroix, the ambassador of Emperor Rudolph II who cheated the latter who wanted to acquire a painting by Dürer from him. The Count offered him a copy instead but the Emperor discovered the trick and put an abrupt end to his mission. A few years later, the Emperor managed to buy the original.
Sometimes artists had to please rival customers regarding one precise masterpiece and in order to avoid trouble they preferred to sell the original to one and its replica to the other. All the more, some princes ordered copies to ornate their different palaces. Most masters had pupils working in their studios and for a start they produced copies before reaching the status of assistant. In addition, during the 17th Century, certain great painters such as Rubens, Van Dyck or Teniers went on to copy Renaissance masters just for sheer pleasure while several kings and nobles were content to obtain replicas of original works they did not manage to acquire from them. In addition, painting was often a family business which lasted over several generations between the 16th and 18th Centuries. Naturally such business generated copies within these families.
The Brueghel family, spearheaded by Pieter the Elder during the 16th Century, was pobably the most famous and is surely the best example to set forth regarding copies. Brueghel's son, also named Pieter, went on to produce scores of replicas of his works while his other sons and next of kin made their names through genre or still-life paintings which often looked alike over more than 75 years.
There were thus countless tribes of artists (Pourbus, Francken, Heemskeerk, Teniers and so on) that flourished sometime during more than a hundred years as from 1560 especially in the Netherlands and Flanders.
Meanwhile, collecting became increasingly popular during the 17th Century as kings like Philip II of Spain, Charles I of England and Louis XIV of France amassed hoards of works of art in their palaces. Otherwise, there were however not many dealers among whom some of them carried out other activities which had little to do with the art trade.
Art galleries were scarce until 1720 and it was from England that the trade reached a more interesting level during the 18th Century when young lords took a habit of embarking on a grand tour of Italy and Greece during which they were visiting archaeological sites and bringing souvenirs back home.
It was during the second half of that century that James Christie inaugurated in London the first true auction house since Roman times soon to be followed by Sotheby's.