At first, bilateral treaties were concluded
on a relatively small scale between neighboring countries.
But after the First World War
an extensive treaty network developed in central Europe.
Germany, for instance, concluded its first double tax agreement with Italy in 1925.
And the United Kingdom, concluded a bilateral tax treaty with Ireland in 1922.
United States concluded tax treaties with Sweden and France in 1939.
This patchwork of differing bilateral treaties stimulated the League of Nations,
the predecessor the current United Nations
and founded in 1920 after World War I to develop a kind of uniform,
model tax treaty.
In 1921, it asked four experts on public finance, Bruins from Rotterdam,
Einaudi from Turin, Seligman from New York, and Stamp from London,
to prepare a report of double taxation which led to a famous publication in 1923.
This publication was subsequently discussed in various sub-committees,
leading to a first model treaty in 1928 and to the model treaty of Mexico in 1943.
In 1946, the model treaty of London was completed.
And after the Second World War, the League of Nations ceased to exist.
It was succeeded by the United Nations.