Although he had the map for guidance, there were no satellites in this day and age, so there was no point expecting too much accuracy from a hand-drawn map. It basically only provided a rough area. On top of that, many dunes in the desert shifted about with the wind, leaving few landmarks to use as references.
As a result, Zhang Heng spent a full month wandering the desert before finding the stone monument Lucilla had mentioned, the one marking the library's entrance. Along the way, Zhang Heng also unexpectedly ran into a band of bandits. Though he ultimately dealt with them all, he still lost two camels and a guide.
The guide had simply been unlucky. When it happened, he had been too far from Zhang Heng and took an arrow to the forehead, dying on the spot. There was nothing Zhang Heng could do about that. He could only pay extra compensation and ask the guide's companions to deliver the money to his family. As for the two camels, they had bolted in fright. That was not much of a problem—once he found the place, he could always resupply food and water in a nearby town if necessary.
Upon reaching the final destination, Zhang Heng said goodbye directly to his two remaining guides. He pitched a tent beside the stone monument, and by the time he had finished his open-air barbecue that evening, the moon had climbed overhead. Following Lucilla's instructions, Zhang Heng waited patiently for a while longer. Once he had confirmed that it was past midnight, he extinguished the campfire and walked roughly fifty paces in the direction indicated by the monument's shadow.
Of course, there was room for error in this method as well. The time was not much of an issue, since Zhang Heng