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tokens: Several molecular clouds and two star formation regions, Sgr B1 and Sgr B2, have been marked in the top panel. In the bottom panel, H ii regions in the GC are labelled, such as H1-8 (Yusef-Zadeh Morris 1987 ). In addition, new H ii regions, identified from our HST /NICMOS Paschen- survey, are outlined in an ellipse, two circles and boxes. Besides H2, several well-known H ii regions, as well as newly discovered ones (Wang etal. 2010 ), fall on to the orbit of molecular clouds and could represent the star formation induced by their pericentre passages. First, we consider H3, H4, H6 and H7, among the eight H ii regions (H 18) identified by Yusef-Zadeh Morris ( 1987 ) in the region between the Arches cluster and Sgr A*. Dong etal. ( 2015 ) show the presence of a single evolved massive star in each centre of H5 and H8. They find that the radial velocities of these stars are significantly different from those of nearby ionized and neutral gas. This indicates that the stars are likely interlopers and did not form in situ . In the other four H ii regions, H3, H4, H6 and H7, no evolved massive stars have been found, although the possibility exists that there are still embedded massive main-sequence stars in these H ii regions. The massive main-sequence stars normally have hydrogen or helium absorption lines. Therefore, they cannot be identified by their Paschen- emission lines in the work by Dong etal. ( 2012 ). Another possibility is that the hydrogen emission lines from the central evolved massive stars are diluted by the emission from the surrounding dust, like the dusty WC stars (Dong etal. 2012 ). Furthermore, H6 and H7 with a size of 0.1pc could be ultracompact H ii regions. Compared to H2, the embedded stars could be less massive and therefore neither have enough ionization luminosities nor have they had time to disperse the surrounding dense molecular gas. Secondly, let us consider several new H ii regions identified by our HST /NICMOS Paschen- survey in the region Galactic West to Sgr A* (see the circles, ellipse and boxes in the bottom panel of Fig. 14 ). The detailed Paschen- image of the H ii region enclosed by the ellipse can be found in fig. 3 of Wang etal. ( 2010 ). All of these regions contain evolved massive stars, such as WN, Ofpe/WN9, WC9d, B supergiant and their candidates (Muno etal. 2006 ; Cotera etal. 1999 ; Mauerhan etal. 2010a , b ; Dong etal. 2012 ). Some of them are close to the molecular cloud orbit, which include those marked by the ellipse and the two circles. Therefore, they may be molecular clouds that have experienced star formation induced by the pericentre passage around Sgr A*. The two regions marked by the boxes are somewhat off the orbit and may have different origins. In conclusion, we have demonstrated that star clusters associated with the H ii regions, aided by the CMD analysis, could help us constrain their ages and the star formation history in the GC. 5 SUMMARY In this work, we have mapped the radial