Fraedrich, K., Jiang, J., Gerstengarbe, F.-W. and Werner, P.C. 1997. Multiscale detection of abrupt climate changes: Application to River Nile flood levels. International Journal of Climatology 17: 1301-1315.
Historical maximum and minimum flood-level time series of the River Nile (AD 622-1470), in the words of the authors, were "chosen to identify abrupt climate changes by applying global and local analysis techniques: the Mann-Kendall test and a non-hierarchical cluster analysis method to improve the Mann-Kendall test; a multi-scale moving t-test with correction to the degree of freedom and an anti-symmetric wavelet transform." This was done because they felt the River Nile and its source regions with their "links to other climatic zones of the world, may represent a key region to demonstrate the possible global nature of climate variability."
The efforts of the four researchers revealed, as they describe it, "three climate epochs of longer time-scales, AD 622-1078, 1079-1325 and 1326-1470, coinciding with larger-scale climate changes reported in Europe: a relatively cool age, the Little Climatic Optimum of the Middle Ages, and an interim period before the Little Ice Age." Hence, we accept their conclusion that the source regions of the River Nile experienced the Medieval Warm Period over the time interval AD 1079-1325.