Wikipedia
Tysyatsky (tysiatsky, ; sometimes translated "dux" or "Heerzog" but more correctly meaning " thousandman" - sometimes translated into the Greek " chiliarch") was a military leader in Ancient Rus, who commanded a people's volunteer army called тысяча (tysyacha, or a thousand). In the Novgorod Republic, the tysyatsky evolved into a judicial or commercial official and was elected from boyars at a veche for a period of one year. Like the posadniks in Novgorod, the office was often held by one man for several years in a row and he was often succeeded by his son or another close relative, indicating that the office was held within clans and was not fully elective. In cities with no veche, tysyatskies were appointed by the knyazs or prince from among the noble boyars and could hand down their post to their sons.
In the Novgorod Republic, tysyatskies were considered representatives of ordinary (black) people. Along with the role as military leaders, they were also supposed to supervise the city fortifications, convene veches, act as ambassadors and as judges in the commercial courts. Like the posadniks, in the 14th century the former tysyatskies maintained considerable political influence and privileges and were known as Old Tysyatskies. The earliest documented tysyatsky of Novgorod was Putyata.
Grand Prince Dmitry Donskoy, after the death of Vassily Vassilyevich Velyaminov in 1374, abolished the post, replacing it with voyevodas and namestniks. The tysyatsky in Novgorod was abolished when Grand Prince Ivan III conquered the city in 1478. It was abolished in Pskov in 1510 when Vasilii III took that city.