1738 years (AD 262–1999) of temperature variability are inferred from tree-ring widths of Siberian pine at Solongotyn Davaa (Sol Dav), a timberline (2420 m) site in Mongolia. This chronology can account for 33% of the temperature variance from 1882–1993. The warmest conditions over the past millennium are during the 20th century. The 1999 ring width has the highest index value over the past millennium. Both warmer and colder intervals are inferred during the “Medieval Warm Epoch”. The most severe cold occurred in the 19th century. Unusual cold and frost in AD 536–545 coincide with extremes in other proxies and historical accounts, confirming a widespread, catastrophic event. Trends resemble those of other Eurasian paleoseries, and hemispheric-scale reconstructions over the past millennium. More chronologies such as Sol Dav are essential to improve coverage in the uncertain earlier centuries of these reconstructions and their estimates of natural variability relative to recent anthropogenic change.