Why 1898-1929? Because those are very poorly documented years. From 1930 on, Gordon May's book "By miles the best" does an excellent job of documenting all motorcycles produced and as we argued before, the books at Royal Enfield Books cover most of the historical material that is available for the later years. See also the excellent Sheldon's European Motorcyle Universe. These are the "museum exhibits":
India wing of the museum.
Note: many of the pictures in the exhibits I have collected over the years from the internet and in many cases I don't know their origin. If you see an attribution problem, please contact me.