@Anonymous , generally as a non-resident alien ( whether you are present in USA or in your own country ), US taxes you ONLY on US sourced / connected income. For US citizen/Resident/ Resident for tax purposes , one is taxed on world income.
As a resident in foreign country , taxation of income from US would come under the purview of any existing tax treaty between US and that "other " country.
Thus , in your particular case , while 1099-misc probably is not valid in your country, it is proof that you were paid a certain amount from US sources and thus us subject to US taxes -- you should look at the tax treaty between US and your country of residence and/or citizenship.
Absent, any other local income during that 1099-misc period, you could simplify the whole process by filing a US tax resident return on form 1040 covering the whole year -- the risk here is that you would be exposing your world income to US taxes.
The correct procedure is to file a form 1040-NR ( not supported by TurboTax -- use Sprintax or similar ) for the earlier period and then file a form 1040 ( supported by TurboTax ) covering the H-1B period i.e the rest of the year. You are essentially in a Dual Status situation.
Depending on when you entered he country, any earlier stays in the country for any purposes etc. , the whole position may change . It may behoove you to see a tax professional familiar with international filing .
If you need help here please provide . your country of residence / citizenship where the earlier work was done, dates associated with this entry into USA, dates and number days present in the USA during years 2017, 2018 and 2019
