How long did the second millennium last?

There may be some doubts about the Western world’s 1st millennium chronology, especially England and East Anglia’s history, but surely there can be no issues with the rather more recent written and recorded 2nd millennium?

The data points represent 5 year averages of tree-ring samples and note particularly the period representing the Maunder Minimum, roughly 1610 to 1690 CE of both graphs. Note also the significant drop in O16/18 ratio known as the Dalton Minimum which seems to coincide with the 1859 Carrington Event in the O16/18 graph (red).

Tree rings are growth rings of particular trees reacting to assumed yearly climate changes, summer and winter. Tree ring dating assumes the Earth has not changed in diurnal rotation, yearly orbit and axial inclination over time. Diurnal rotation around its axis might vary if the Earth’s diameter has changed, however.
2nd Millennium Achronological Issues | Louis Hissink

If historians dismiss 1st millennium New Chronology revisionism as attention seeking histrionics by amateurs then what would they say about any attempts to rewrite our historical timelines?

Ancient civilizations structures could be interpreted as physical evidence for changes in our planet’s rotational properties. Although not 2nd millennium but perhaps one example of megalithic buildings used to measure orbital variations such as a rapid change in Earth’s horizon (inclination) are on the Islands of Malta. C R Sant has investigated and written The Calendars of Megalithic Malta: Resolving their Functions and Anomalies.