The Tang dynasty was the last period when the great aristocratic families, mostly descended from the nobility of pre-Qin states, held significant centralized and regional power. The surname was used as a source of prestige and common allegiance. During the period many genealogical records called "pudie" () were compiled to trace the complex descent lines of families or clans and their marriage ties to other families or clans. Many of these were collected by Ouyang Xiu in his "New History of Tang". To differentiate between different surnames, the Tang also choronyms before stating beforehand, for example Lǒngxī Lǐshì 隴西李氏, meaning Li of Longxi. These were generally the names of commanderies used prior to the reorganization during the Tang, so that they became exclusively associated to clans as their common use had died out. Cadet branches were also listed for further differentiation, such as Gūzāng Fáng 姑臧房, meaning Clan Li of Guzang.