Spreading of forests at the beginning of the Holocene marks the transition to warmer conditions. From 10.7 to 4.4 cal kyr BP open Abies–Betula forests were found at Lake Naleng probably reflecting a stronger-than-present summer monsoon. Temperature range reconstructions suggest a temperature that was about 2–3 °C warmer and a treeline position that was 400–600 m higher than today. A severe climate deterioration with temperatures about 1–2 °C colder than before is documented by a retreating forest between 8.1 and 7.2 cal kyr BP. Forests retreated while subalpine Rhododendron shrubs spread around Lake Naleng indicating colder conditions with temperatures 1–2 °C below early and mid Holocene level after 4.4 cal kyr BP. The forest decline at 4.4 cal kyr BP is considered to reflect climatic conditions as low concentrations of charcoal particles found in this period exclude human-induced fires as reason for the forest retreat. However, grazing indicators imply human influence on the environment since 3.4 cal kyr BP around Lake Naleng. We therefore consider the rapid treeline shift seen at 3.4 cal kyr BP as partly generated by human activity and partly by climatic conditions.