Defeated Pechenegs not slaughtered, but settled as taxpayers & potential soldiers in Bulgaria

Summary:
The advice of Kegen was that all adult Pecheneg captives should be killed, citing a barbarian proverb according to which it is better to kill a serpent in winter while it cannot move its tail. Those he held personally were either sold into slavery or slaughtered. This proposal was rejected as barbaric, unholy, and unworthy of Roman clemency. The emperor and generals decided that the captives would be useful to the Romans if, after putting aside their weapons, they were settled in the Bulgarian land, which was largely depopulated after long periods of war. Basileios the doux (?) of Bulgaria took the lead in this, settling them particularly in the the plains of Serdica, Nis and Eutzapolis 
Dates:
1047 
Basileios, governor (?) of Bulgaria (Basileios 109)
  • Took the thousands of Pecheneg captives and settled them in the plains of Serdica, Naissus and Eutzapolis, dispersing and disarming them (following the decision that it would be more profitable to settle and tax them rather than execute them) (:) Skylitzes 459.80-83
Kegen, Pecheneg leader (Kegen 101)
  • Advised to execute all the adult (Pecheneg) captives, citing a barbarian proverb according to which it is better to kill a serpent in winter while it cannot move its tail, but his suggestion was deemed barbaric, unholy, and unworthy of Roman clemency (:) ἔτι χειμῶνος ὄντος δεῖ τὸν ὄφιν ἀποκτεῖναι, ὁπηνίκα τὴν κέρκον κινεῖν οὐ δύναται Skylitzes 459.67-72
  • Although his advice to execute the Pechenegs who had surrendered was rejected by the commanders of the Roman army, he executed all his captives apart from those he had sold off (to slavery) and returned home (:) Skylitzes 459.78-79
  • Of those Pechenegs who came into his hands, some were consigned to the sword, others were sold into slavery for gold (:) Zonaras 17.26.17
Emperor Konstantinos IX Monomachos (Konstantinos 9)
  • At his command, the remaining multitude of Pechenegs were considered useful to the Romans if, after putting aside their weapons, they were settled in the Bulgarian land, which was largely deserted, since that nation had been put down shortly before (:) Zonaras 17.26.18