Mori Kaoru is a master of the rapid tonal shift. I think that fits a story of life in a pre-industrial society very well, because life in such a society is a succession of rapid tonal shifts. Even minor (by modern first-world standards) illnesses could be fatal. Danger could appear at any moment from anywhere, but daily life was often drudgery or idyll. When stuff happens, it happens fast – and you have to be ready for it or potentially pay a severe price.
Out of nowhere, bandits appear on the road. They choose a narrow mountain pass, a perfect place from which to waylay travelers. It was for this that Nikolovksy (thankfully) came along on this journey and indeed, extended his stay beyond his planned turnaround in Baghdad. Between Nikolovsky and Ali Mr. Smith and Talas are in good hands, but this is still a life-and-death situation. Ali spots the danger quickly but the party is still being fired upon by several armed attackers.
These are not professional thieves or soldiers, as it happens – just locals forced to turn to banditry by the times. If they had been it’s likely things wouldn’t have ended with something far worse than sand in the eyes, but their presence itself is still a dire signal. Amateur bandits mean that warfare has afflicted the area, just as Smith was warned. And that means continuing this journey is considerably risky. Mr. Smith had said all along that he’d leave it to Ali to decide whether they reached a point where he’d turn back if he were on his own, but at this point I suspect Ali is emotionally committed to getting Smith to where he wants to go.
Also of note here is that Talas proves herself to be pretty nifty in a fight. Especially where the horses are concerned. It’s her quick thinking which prevents a disaster, as she chases down Smith’s panicked horse and coaxes him back to the others. But it’s naive to think the rest of this journey is going to be free of trouble. All the more so if it represents the climactic arc of the series.