In 1946 a US-firm, H. P. Products Co., begun to produce model railroading equipment in scale 1:120 (It was a response to Half-0 (HO) and was "Half-S"). The new model railroad had to find room on a table, therefore the name "Table Top".   The UK produced Triang models in TT (I don't have any more information). At the Nuremberger Toy-fair in 1950, Rokal, up to that time known for their auto branch, presented the first German TT-products.Although the models weren't exactly 1:120, the new scale found many friends. (The flat economic situation after the war favored smaller scales). But TT wasn't born under lucky stars: problems inside the firm, unfortunate marketing policy and the death of the manager caused the end of the big TT mass production in the Western countries in the early 70's. The firm was bought by Röwa, which didn't continue the Rokal-program, but saved the forms. In the Western countries only a small capacity of the production remained, e.g. Dr. Kunze, Krüger, Kroner and Beckmann, but in the last years the number of such producers fortunate increased.

In the GDR Zeuke&Wegwerth began to produce the first, owner developed TT-models in 1958. The firm was later nationalized and as VEB Berliner TT-Bahnen (BTTB) was the only mass-producer, representing this forgotten scale. Unfortunately without concurrent companies the development of quality of models was reduced. Several models of the company are produced in the same way, or with little change, more than 35 years later. But what then was up-to-date, is now underdeveloped.
According to careful estimations in the late 80's, 40% of model railroaders in the GDR "traveled" with this scale. This is probable due to the fact that there are so many TT friends in the ex-East-Block states.

After the reunification of Germany in 1990, it was questionable if any of the manufacturers in the GDR would remain in business. Many people in these years turned to H0 or N, but there were people who didn't give up and persisted in TT. They were right. BTTB has been bought by the owner of Pilz and MaTTra and since that time the production goes under his name, Tillig. The product-range has been thinned out and partly reworked, e.g. some of their new engines have a place for a digital decoder.
 
A Western firm Arnold well known for its "N" scale branch, launched the production with a shunter locomotive. About 1994 the Austrian firm Roco flirted with the idea of producing TT-models. TT was even entered in their catalog. But the idea has failed. (In my opinion, they should have been a great success.) The planned models were reworked Rokal models, because these forms went to Roco from Röwa.
And in 1998 happened the wonder: at the Nuremberger Toy-fair Roco presented a new constructed model of the diesel locomotive BR 232 and showed protoypes of some freight cars. Some of them will be realised in year 1999.
 
At present there are manufacturers in Germany, Netherlands, Czechia, Russia, Suisse, Austria, Poland and Hungary producing something in TT scale. According to some information there is a manufacturer in the USA, too.