Tan Daoji was a celebrated general during the reigns of Emperor Wu and Emperor Wen of the Liu Song Dynasty, having achieved numerous military victories.
During a campaign against the Northern Wei, General Tan Daoji led his Southern forces to over thirty victories, pushing deep into Shandong near Licheng. But as supplies and rations dwindled, he ordered a retreat southward.
At that moment, a soldier from the southern army secretly slipped into the Northern Wei camp and reported that the southern army's food supplies were nearly exhausted. The Northern Wei commanders were overjoyed and immediately ordered their forces to pursue the southern army from behind. The southern soldiers, gripped by fear, found their morale crumbling in an instant.
General Tan Daoji was deeply worried, knowing that if the enemy caught up, his army would surely be defeated. After much thought, he devised a clever plan. He ordered his trusted officers to secretly haul in piles of sand under cover of darkness, then loudly counted as they measured it, finally sprinkling a small amount of leftover rice over the heaps. In the dim night, these looked exactly like mountains of grain. Seeing this, the southern troops' morale soared.
At dawn, Northern scouts spotted these "rice mountains" and, believing the Southern army had ample supplies, dared not pursue and withdrew, even executing the informant. The idiom "Singing Tallies While Measuring Sand" refers to using sand as rice and counting it out loud to fake abundant grain stores, illustrating how one creates illusions to steady morale and deceive the enemy.
Source: *History of the Southern Dynasties*, "Biography of Tan Daoji"
Meaning of the Idiom: Later, the Chinese idiom "唱筹量沙" came to describe how one creates illusions to steady morale and deceive the enemy.