Green’s Dictionary of Slang

(Anglo-Ind.) excl. used to urge movement, ‘go on!’.

1850		Indian Sporting Rev. 222: About a hundred beaters are then put in line, with flags to keep them level with each other, and tomtoms ‘chullo’.
1860		T. Prichard Mutinies in Rajpootana 303: I saw some natives running about wildly, and presently several shots were fired not far from where I was standing. ‘Chullo, sahib! gole chulte,’ said the naick, who now entreated me to leave the place, or I should be killed.
1867		J.T. Newall Hog Hunting in the East 130: ‘But the chance is good, and the sahib’s nuseeb is great. I will show them if they are there. Chulo (get along), brothers.’.
1887		J.C. Fife-Cookson Tiger-shooting in the Doon and Ulwar 7: ‘Chalo bhai!’ (Go on, brother!) screams the driver, as he hits the horse on the off side a hard whack with his whip; the animal jerks its head nervously from side to side once or twice, but shows no signs of moving.
1897		S.H. Jones-Parry Old Soldier’s Memories 198: A dispute was going on as to who should lead the assault. At last it seems that a leader was chosen, and then came the cry from the others, ‘Chullo Bahadoor! Chullo Bahadoor!’‘Go on, sir; lead on, sir!’.
1900		B.M. Croker Odds and Ends 164: Lovett sprang into the gharry shouting the word ‘Chullo!’ and was soon swept out of the station, in a cloud of dust.