What do these numbers refer to?Give situations 1835 1856 1842 1850 1861 1857 1865 1858 Помгите плиз дам 35 Балов

one thousand eight hundred thirty five-1835
one thousand eight hundred fifty six-1856
thousand eight hundred fifty-1850
one thousand eight hundred forty two-1842
one thousand eight hundred fifty seven-1857
one thousand eight hundred fifty eight-1858
one thousand eight hundred sixty one-1861
one thousand eight hundred sixty five-1865