David is best known for his crucial assistance to the Byzantine Macedonian dynasty in the 976–9 civil war and his unique role in the political unification of various Georgian polities as well as his patronage of Christian culture and learning.

[citation needed] He succeeded his brother, Bagrat II, as a duke of Tao in 966, and through his expansionist policy and flexible diplomacy began assembling a larger state.

The Byzantines' eastern neighbors – the fragmented Armenian and Georgian principalities – rarely threatened the empire directly, but were of particular interest to Constantinople as they controlled strategic international trade routes that ran through their domains.

In the urgency of a situation, the young emperor Basil requested aid from David of Tao, who promptly responded and sent 12,000 first-rate cavalry troops under the command of Tornikios to reinforce the recently defeated loyal Byzantine general Bardas Phokas, thereby contributing to the decisive loyalist victory at the Battle of Pankalia near Caesarea on 24 March 979.

[3] The medieval Georgian authors call him "greatest of all the kings of Tao"[5] and the eleventh-century Armenian chronicler Aristakes Lastivertsi describes him as: a mighty man, a builder of the world, very honorable, a lover of the poor, indeed, the definition of peace.

[6]Being in control of highly important commercial centers, his principality profited from taxing the major trading routes running through southwestern Caucasus and eastern Anatolia.

David invested these revenues in extensive building projects: constructing towns, forts and churches, and promoting Georgian monastic communities and cultural activities both in Georgia and abroad.

David's good fortunes changed in 987 when he, anxious to make his extensive possessions a hereditary Bagratid domain, joined his long-time friend Bardas Phokas in a rebellion against the emperor Basil.

Persuaded that his foster-son intended to attack Tao and kill him, David crushed the army led by Bagrat's natural father Gurgen on its march to Kldekari.

Despite this setback, Bagrat was able to become the first king of an all-Georgian unified monarchy,[10] a result made possible largely by the efforts of David of Tao, who, as the modern scholar Stephen Rapp puts in, "appropriately ranks high on any 'Top Ten' list of Georgian history.

"[11] There is some disagreement among modern scholars on whether David ceded to the Byzantines only those lands which had been granted to him as a reward for his assistance against the rebel Bardas Skleros, or if it had been the whole of his principality that was acquired by Basil II.