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High-redshift blazars are valuable tools to study the early Universe. So faronly a handful of $\gamma$-ray blazars have been found at redshifts above 3.$\gamma$-ray signals are detected in the direction of PMN J2219-2719 ($z=3.63$)and PMN J2321-0827 ($z=3.16$) by analyzing the 10-year $Fermi$-LAT Pass 8 data.PMN J2219-2719 is not distinguished from the background in the global analysis.During the 5-month epoch, the TS value is 47.8 and the flux is more than 10times of the 10-year averaged flux. In addition, the angular distance betweenthe $\gamma$-ray position and the radio position of PMN J2219-2719 is only${0.04}^{\circ}$. Moreover, the $\gamma$-ray and infrared light curves of longtime scale are very similar, which support the association between the$\gamma$-ray source and PMN J2219-2719. The global analysis of PMN J2321-0827suggest a new $\gamma$-ray source, during the flare phase, the TS value is 61.4and the $\gamma$-ray flux increased significantly. The association probabilitysuggests that PMN J2321-0827 may be the counterpart of the new $\gamma$-raysource. In the future, the number of high-redshift $\gamma$-ray sources willincrease by combining $Fermi$-LAT and the upcoming Large Synoptic SurveyTelescope.

Awakening of two $\gamma$-ray high redshift flat-spectrum radio quasars in the southern hemisphere