  We present a Chandra and XMM-Newton study of the SNR CTB 37B, along with
archival radio observations. In radio wavelengths, CTB 37B is an incomplete
shell showing bright emission from the eastern side while the X-ray morphology
shows diffuse emission from regions surrounding the magnetar CXOU
J171405.7-381031. We used archival HI absorption measurements to constrain the
distance to the remnant as 9.8+/-1.5 kpc. The X-ray spectrum of the remnant is
described by a thermal model in the 1-5 keV energy range, with a temperature of
1.3+/-0.1 keV. The abundances from the spectral fits are consistent with being
solar or sub-solar. A small region of diffuse emission is seen to the southern
side of the remnant, best fitted by a nonthermal spectrum with an unusually
hard photon index of 1.3+/-0.3. Assuming a distance of 9.8 kpc to the SNR, we
infer a shock velocity of 915+/-70 km/s and explosion energy of (1.8+/-0.6)e50
ergs. The overall imaging and spectral properties of CTB 37B favor the
interpretation of a young SNR (6200 yr) propagating in a low-density medium,
under the assumption of a Sedov evolutionary phase.
