Query: Along with centralization, what reason is given for the lack of records in non-Wessex dialects after the unification of Alfred?
Context: Due to the centralisation of power and the Viking invasions, there is relatively little written record of the non-Wessex dialects after Alfred's unification. Some Mercian texts continued to be written, however, and the influence of Mercian is apparent in some of the translations produced under Alfred's programme, many of which were produced by Mercian scholars.