Eastern Asia: in northern Japan. northern China, Korea, and far southeastern Russia.
Syringa reticulata is a deciduous small tree growing to a height of 39' (12 m), rarely to 49' (15 m), with a trunk up to 11.8" (30 cm), rarely 15.7" (40 cm) diameter; it is the largest species of lilac, and the only one that regularly makes a small tree rather than a shrub. (Wikipedia)
Although the most popular cultivars of this species have been in the landscape trade for over 25 years, only recently is it finding its way into our landscapes in a more consistent fashion. (Nebraska Forest Service http://nfs.unl.edu/CommunityForestry/Trees/TreeLilac.pdf)