  Using $525$ pb$^{-1}$ data collected with the BESIII detector at $e^+e^-$
central-of-mass energy 4.26 GeV, the BESIII Collaboration observed a charged
charmoniumlike state $Z_c(3900)\to\pi^{\pm}J/\psi$ with mass
$M[Z_c(3900)]=3899.0\pm 3.6 \pm 4.9$ MeV/c$^2$, and width
$\Gamma[Z_c(3900)]=46\pm 10 \pm 20$ MeV. The significance of this state was
estimated to be $>8\sigma$ in all kinds of systematic tests. Using $967$
fb$^{-1}$ data recorded by the Belle detector on or near $\Upsilon(nS)$, n=1,
2, $\cdots$, 5 resonances, the $e^+e^- \to \pi^+\pi^-J/\psi$ process has been
studied through initial-state-radiation (ISR) method. Except for the $Y(4260)$
resonance, an intermediate state $Z(3900)^{\pm}$ has been observed in the
$\pi^{\pm}J/\psi$ mass spectrum, with significance $>5.2\sigma$. The measured
mass $M[Z(3900)^{\pm}]=3894.5\pm6.6\pm4.5$ MeV/c$^2$ and width
$\Gamma[Z(3900)^{\pm}]=63\pm24\pm26$ MeV, shows good agreement with the BESIII
measurement within errors, which means $Z_c(3900)$ and $Z(3900)^{\pm}$ is the
same state.
