The old client was used from update 1.0 to 7.0. The graphics were really poor, and the map was much smaller back then, including only Thais, Carlin, Kazordoon, Ab'Dendriel, Edron and Darashia. The only world that existed until late 2001 was Antica.
For a timeline, see Updates.
Bubble reaching level 100
Another example of the old client