B. Mathew has written somewhere that what was depicted in Minoan frescoes could well be the harvest of saffron from C. cartwrightianus because white flowers were also painted.
I am not convinced by a natural hybridization involving C. thomasii and C. cartwrightianus because of the geographical distribution of these two crocuses (map Fig 3 p 6, reference given by Aaron) - unless the crossing was man made and artificial, which is also possible, or unless C. thomasii was artificially cultivated with C. cartwrightianus in the same garden (after all, commercial exchanges existed and a certain degree of civilization existed in the empires of the past).
A natural mutation in C. cartwrightianus seems more plausible regarding genetic closeness with C. sativus and visual resemblance of the plants, am I wrong ?