In article . com,
wrote:

However, the
history indicated that the first professional digital camera, the
Nikon D1 was introduced in June 1999. Canon only was able to match
that by the introduction of its EOS-1D in Sept 2001, 2 years behind
Nikon's first DSLR.

you skipped the old kodak slrs that go back to the mid-90s which were
based off nikon and canon film bodies as well as the canon d30 that
came out in may, 2000, and for roughly half the price of the nikon d1.

nikon updated the d1 to the d1h and d1x in january, 2001, followed by
the canon 1d in september 2001. there was also the short lived contax
full frame dslr announced in july, 2000 and the pentax full frame dslr,
shown in february 2001 and later cancelled.

But the numbering system suddenly
clashed recently with the introduction of the new Canon 40D versus
Nikon D40 and D40x, as well as Nikon's new D300 vs. the older Canon
350D or 400D (Rebel Xti). So 40D is Canon and D40 is Nikon....... a
very confusing brand numbering system!

what's even more confusing is the canon d30 and 30d, two very different
cameras. there is also the konica/minolta 5d and canon 5d.