Use the Future Machine.
Both the start and end of the Time Tangled quest are in 2059 (50 years from the present). The "time device" travels back in time from the present. When you have completed the quest (all times show green), the "lab" at 12 o'clock will flash to let you know to return to Professor Pendulum's lab and the Future Machine.
The Vikings are at 831 AD (2 o'clock on the time device).
831 AD this is the viking "year".
Vikings (831 AD)
The Aztec Empire is where you get the sun stone piece on Time Tangled Island. It is 1519 AD the picture is a man with headdress.
The cave is located in 0831 AD.
The Vikings at 831 AD.
Thomas Jefferson is at 1776 AD on Time Tangled Island (7 o'clock on the time device). His Declaration of Independence is at the Timbuktu Inn at 1387 AD (3 o'clock on the time device). The salt rocks for 1387 AD are on the roof of Jefferson's residence.
You can copy armor from the characters there and on Astro Knights Island.Also, at 831 AD on Time Tangled Island, there is a Viking Suit. (see the related question)
There is no paint brush as an item on Time Tangled Island. There is at least one in the scene at the workshop of Leonardo Da Vinci (1516 AD).
This is a non-specific description of the symbol for the Mali Empire, 1387 AD, on Time Tangled Island. This time period is the 3 o'clock position on the time device.
The Vikings are at 831 AD, which is 2 o'clock on the time device.
The Aztecs are at 1519 AD (5 o'clock on the time device).