Abstract: Based on well-known series from land-based caves and reconstructed sunspot numbers, the nature of climatic response to solar variability is discussed over a long-time scale. Wavelet analysis reveals coherence between the climatic and solar oscillations with periods of ～1000- and ～2000-yr that may reflect a modulation of solar activity during the Holocene. Moreover, the wavelet power spectra present that ～1000-yr cycle of these series is absent around ～2000 BC and this abrupt change and prolonged changes in climatic conditions might have brought about major societal challenges to many regions.