Through the Italian National Broadcasting Network, Tezuka Osamu received an ardent request from the Vatican to make the Bible into animated form. This request was probably made to see how the Bible would be depicted by the non-Christian Tezuka Osamu. Tezuka Osamu accepted the request and spent an entire two years to complete a pilot film. It was about the mythology of Noah's ark, with the enthusiastic Tezuka Osamu not only writing the scenario but also drawing pictures by himself. During production, however, he unfortunately passed away, so Director Dezaki took over the film and completed it.
(Source: official homepage)
Note: While the series was in production during a period of several years in the late 1980s and early 1990s, it was not aired in Japan until 1997, on the satellite channel WOWOW. It was most likely broadcasted in Italy in 1992.